diff --git a/src/blackcore/context/contextsimulator.h b/src/blackcore/context/contextsimulator.h
index 0c41c3c24..a1e636ee7 100644
--- a/src/blackcore/context/contextsimulator.h
+++ b/src/blackcore/context/contextsimulator.h
@@ -151,7 +151,7 @@ namespace BlackCore
             virtual int getModelSetCount() const = 0;
 
             //! Models for model string
-            virtual BlackMisc::Simulation::CAircraftModelList getModelSetModelsStartingWith(const QString modelString) const = 0;
+            virtual BlackMisc::Simulation::CAircraftModelList getModelSetModelsStartingWith(const QString &modelString) const = 0;
 
             //! Model strings
             virtual QStringList getModelSetStrings() const = 0;
diff --git a/src/blackcore/context/contextsimulatorempty.h b/src/blackcore/context/contextsimulatorempty.h
index 42ad90fdf..39ccebd96 100644
--- a/src/blackcore/context/contextsimulatorempty.h
+++ b/src/blackcore/context/contextsimulatorempty.h
@@ -103,7 +103,7 @@ namespace BlackCore
             }
 
             //! \copydoc IContextSimulator::getModelSetModelsStartingWith
-            virtual BlackMisc::Simulation::CAircraftModelList getModelSetModelsStartingWith(const QString modelString) const override
+            virtual BlackMisc::Simulation::CAircraftModelList getModelSetModelsStartingWith(const QString &modelString) const override
             {
                 Q_UNUSED(modelString);
                 logEmptyContextWarning(Q_FUNC_INFO);
diff --git a/src/blackcore/context/contextsimulatorimpl.cpp b/src/blackcore/context/contextsimulatorimpl.cpp
index 09583ebaa..09b619d35 100644
--- a/src/blackcore/context/contextsimulatorimpl.cpp
+++ b/src/blackcore/context/contextsimulatorimpl.cpp
@@ -183,7 +183,7 @@ namespace BlackCore
             return getModelSet().size();
         }
 
-        CAircraftModelList CContextSimulator::getModelSetModelsStartingWith(const QString modelString) const
+        CAircraftModelList CContextSimulator::getModelSetModelsStartingWith(const QString &modelString) const
         {
             if (m_debugEnabled) { CLogMessage(this, CLogCategory::contextSlot()).debug() << Q_FUNC_INFO << modelString; }
             if (m_simulatorPlugin.first.isUnspecified())
diff --git a/src/blackcore/context/contextsimulatorimpl.h b/src/blackcore/context/contextsimulatorimpl.h
index 42b291c93..d90dc009f 100644
--- a/src/blackcore/context/contextsimulatorimpl.h
+++ b/src/blackcore/context/contextsimulatorimpl.h
@@ -87,7 +87,7 @@ namespace BlackCore
             virtual QStringList getModelSetStrings() const override;
             virtual QStringList getModelSetCompleterStrings(bool sorted) const override;
             virtual int getModelSetCount() const override;
-            virtual BlackMisc::Simulation::CAircraftModelList getModelSetModelsStartingWith(const QString modelString) const override;
+            virtual BlackMisc::Simulation::CAircraftModelList getModelSetModelsStartingWith(const QString &modelString) const override;
             virtual BlackMisc::PhysicalQuantities::CTime getTimeSynchronizationOffset() const override;
             virtual bool setTimeSynchronization(bool enable, const BlackMisc::PhysicalQuantities::CTime &offset) override;
             virtual bool isTimeSynchronized() const override;
diff --git a/src/blackcore/context/contextsimulatorproxy.cpp b/src/blackcore/context/contextsimulatorproxy.cpp
index ad0db15e1..7e39b6b5e 100644
--- a/src/blackcore/context/contextsimulatorproxy.cpp
+++ b/src/blackcore/context/contextsimulatorproxy.cpp
@@ -113,7 +113,7 @@ namespace BlackCore
             return m_dBusInterface->callDBusRet<QStringList>(QLatin1String("getModelSetCompleterStrings"), sorted);
         }
 
-        CAircraftModelList CContextSimulatorProxy::getModelSetModelsStartingWith(const QString modelString) const
+        CAircraftModelList CContextSimulatorProxy::getModelSetModelsStartingWith(const QString &modelString) const
         {
             return m_dBusInterface->callDBusRet<BlackMisc::Simulation::CAircraftModelList>(QLatin1String("getModelSetModelsStartingWith"), modelString);
         }
diff --git a/src/blackcore/context/contextsimulatorproxy.h b/src/blackcore/context/contextsimulatorproxy.h
index a57b34c0f..12d0fb062 100644
--- a/src/blackcore/context/contextsimulatorproxy.h
+++ b/src/blackcore/context/contextsimulatorproxy.h
@@ -67,7 +67,7 @@ namespace BlackCore
             virtual BlackMisc::Simulation::CSimulatorInfo simulatorsWithInitializedModelSet() const override;
             virtual QStringList getModelSetStrings() const override;
             virtual QStringList getModelSetCompleterStrings(bool sorted) const override;
-            virtual BlackMisc::Simulation::CAircraftModelList getModelSetModelsStartingWith(const QString modelString) const override;
+            virtual BlackMisc::Simulation::CAircraftModelList getModelSetModelsStartingWith(const QString &modelString) const override;
             virtual int getModelSetCount() const override;
             virtual BlackMisc::Simulation::CSimulatorInternals getSimulatorInternals() const override;
             virtual bool setTimeSynchronization(bool enable, const BlackMisc::PhysicalQuantities::CTime &offset) override;
diff --git a/src/blackcore/db/databasereader.cpp b/src/blackcore/db/databasereader.cpp
index 8ecf22928..ef721151f 100644
--- a/src/blackcore/db/databasereader.cpp
+++ b/src/blackcore/db/databasereader.cpp
@@ -318,7 +318,7 @@ namespace BlackCore
             return m_sharedFileResponses[entity].getLastModifiedTimestamp();
         }
 
-        bool CDatabaseReader::requestHeadersOfSharedFiles(const CEntityFlags::Entity &entities)
+        bool CDatabaseReader::requestHeadersOfSharedFiles(CEntityFlags::Entity entities)
         {
             if (!this->isNetworkAccessible())
             {
diff --git a/src/blackcore/db/databasereader.h b/src/blackcore/db/databasereader.h
index 7bd8863ef..cd5a2ebaa 100644
--- a/src/blackcore/db/databasereader.h
+++ b/src/blackcore/db/databasereader.h
@@ -204,7 +204,7 @@ namespace BlackCore
             BlackMisc::Network::CEntityFlags::Entity getEntitesWithNewerHeaderTimestamp(BlackMisc::Network::CEntityFlags::Entity entities) const;
 
             //! Request header of shared file
-            bool requestHeadersOfSharedFiles(const BlackMisc::Network::CEntityFlags::Entity &entities);
+            bool requestHeadersOfSharedFiles(BlackMisc::Network::CEntityFlags::Entity entities);
 
             //! Count from info objects
             //! \sa BlackCore::Db::CInfoDataReader
diff --git a/src/blackcore/inputmanager.cpp b/src/blackcore/inputmanager.cpp
index b98217743..235e8013a 100644
--- a/src/blackcore/inputmanager.cpp
+++ b/src/blackcore/inputmanager.cpp
@@ -72,7 +72,7 @@ namespace BlackCore
     void CInputManager::ps_changeHotkeySettings()
     {
         m_configuredActions.clear();
-        for (CActionHotkey actionHotkey : m_actionHotkeys.getThreadLocal())
+        for (const CActionHotkey &actionHotkey : m_actionHotkeys.getThreadLocal())
         {
             if (!actionHotkey.getApplicableMachine().isFromLocalMachine()) { continue; }
             CHotkeyCombination combination = actionHotkey.getCombination();
diff --git a/src/blackcore/pluginmanager.cpp b/src/blackcore/pluginmanager.cpp
index 63db827ef..a8c0bf971 100644
--- a/src/blackcore/pluginmanager.cpp
+++ b/src/blackcore/pluginmanager.cpp
@@ -91,7 +91,7 @@ namespace BlackCore
         return m_instanceIds.value(instance, QString());
     }
 
-    bool IPluginManager::tryLoad(QString path)
+    bool IPluginManager::tryLoad(const QString &path)
     {
         if (!QLibrary::isLibrary(path))
         {
diff --git a/src/blackcore/pluginmanager.h b/src/blackcore/pluginmanager.h
index 55aeb0048..b83ef41d6 100644
--- a/src/blackcore/pluginmanager.h
+++ b/src/blackcore/pluginmanager.h
@@ -79,7 +79,7 @@ namespace BlackCore
 
     private:
         //! Tries to load the given plugin.
-        bool tryLoad(QString path);
+        bool tryLoad(const QString &path);
 
         //! Loads the given plugin (if necessary) and returns its instance.
         //! Returns `nullptr` on failure.
diff --git a/src/blackcore/tokenbucket.cpp b/src/blackcore/tokenbucket.cpp
index 767ec3e46..83abf863a 100644
--- a/src/blackcore/tokenbucket.cpp
+++ b/src/blackcore/tokenbucket.cpp
@@ -14,7 +14,7 @@
 
 namespace BlackCore
 {
-    CTokenBucket::CTokenBucket(int capacity, BlackMisc::PhysicalQuantities::CTime interval, int numTokensToRefill)
+    CTokenBucket::CTokenBucket(int capacity, const BlackMisc::PhysicalQuantities::CTime &interval, int numTokensToRefill)
         : m_capacity(capacity), m_interval(interval), m_numTokensToRefill(numTokensToRefill) {}
 
     bool CTokenBucket::tryConsume(int numTokens)
diff --git a/src/blackcore/tokenbucket.h b/src/blackcore/tokenbucket.h
index 2ae0a15cc..cb631142b 100644
--- a/src/blackcore/tokenbucket.h
+++ b/src/blackcore/tokenbucket.h
@@ -27,7 +27,7 @@ namespace BlackCore
     {
     public:
         //! Constructor for given replenishment policy
-        CTokenBucket(int capacity, BlackMisc::PhysicalQuantities::CTime interval, int numTokensToRefill);
+        CTokenBucket(int capacity, const BlackMisc::PhysicalQuantities::CTime &interval, int numTokensToRefill);
 
         //! Try to consume a number of tokens
         bool tryConsume(int numTokens = 1);
diff --git a/src/blackcore/vatsim/networkvatlib.cpp b/src/blackcore/vatsim/networkvatlib.cpp
index 26c423931..323772d88 100644
--- a/src/blackcore/vatsim/networkvatlib.cpp
+++ b/src/blackcore/vatsim/networkvatlib.cpp
@@ -278,7 +278,7 @@ namespace BlackCore
             }
         }
 
-        QByteArray CNetworkVatlib::toFSD(QString qstr) const
+        QByteArray CNetworkVatlib::toFSD(const QString &qstr) const
         {
             Q_ASSERT_X(m_fsdTextCodec, Q_FUNC_INFO, "Missing codec");
             return m_fsdTextCodec->fromUnicode(qstr);
@@ -289,7 +289,7 @@ namespace BlackCore
             return toFSD(callsign.getStringAsSet());
         }
 
-        std::function<const char **()> CNetworkVatlib::toFSD(QStringList qstrList) const
+        std::function<const char **()> CNetworkVatlib::toFSD(const QStringList &qstrList) const
         {
             QVector<QByteArray> bytesVec;
             for (auto i = qstrList.cbegin(); i != qstrList.cend(); ++i)
diff --git a/src/blackcore/vatsim/networkvatlib.h b/src/blackcore/vatsim/networkvatlib.h
index 50f244116..0725b3365 100644
--- a/src/blackcore/vatsim/networkvatlib.h
+++ b/src/blackcore/vatsim/networkvatlib.h
@@ -163,9 +163,9 @@ namespace BlackCore
             static void onCustomPacketReceived(VatSessionID, const char *callsign, const char *packetId, const char **data, int dataSize, void *cbvar);
             //! @}
 
-            QByteArray toFSD(QString qstr) const;
+            QByteArray toFSD(const QString &qstr) const;
             QByteArray toFSD(const BlackMisc::Aviation::CCallsign &callsign) const;
-            std::function<const char **()> toFSD(QStringList qstrList) const;
+            std::function<const char **()> toFSD(const QStringList &qstrList) const;
             QString fromFSD(const char *cstr) const;
             QStringList fromFSD(const char **cstrArray, int size) const;
             bool isInterimPositionUpdateEnabledForServer() const;
diff --git a/src/blackcore/vatsim/vatsimdatafilereader.cpp b/src/blackcore/vatsim/vatsimdatafilereader.cpp
index 6c8c31a28..e5e13b606 100644
--- a/src/blackcore/vatsim/vatsimdatafilereader.cpp
+++ b/src/blackcore/vatsim/vatsimdatafilereader.cpp
@@ -245,7 +245,7 @@ namespace BlackCore
                 Section section = SectionNone;
 
                 QString currentLine; // declared outside of the for loop, to amortize the cost of allocation
-                for (QStringRef clRef : lines)
+                for (const QStringRef &clRef : lines)
                 {
                     if (this->isAbandoned())
                     {
diff --git a/src/blackcore/vatsim/vatsimstatusfilereader.cpp b/src/blackcore/vatsim/vatsimstatusfilereader.cpp
index 3d4bf3be9..db18273cc 100644
--- a/src/blackcore/vatsim/vatsimstatusfilereader.cpp
+++ b/src/blackcore/vatsim/vatsimstatusfilereader.cpp
@@ -111,7 +111,7 @@ namespace BlackCore
                 CUrlList metarFileUrls;
 
                 QString currentLine; // declared outside of the for loop, to amortize the cost of allocation
-                for (QStringRef clRef : lines)
+                for (const QStringRef &clRef : lines)
                 {
                     if (this->isAbandoned())
                     {
diff --git a/src/blackmisc/aviation/adfsystem.h b/src/blackmisc/aviation/adfsystem.h
index e77a37db7..a4d3cceb7 100644
--- a/src/blackmisc/aviation/adfsystem.h
+++ b/src/blackmisc/aviation/adfsystem.h
@@ -45,7 +45,7 @@ namespace BlackMisc
             { }
 
             //! Valid aviation frequency?
-            static bool isValidFrequency(PhysicalQuantities::CFrequency f)
+            static bool isValidFrequency(const PhysicalQuantities::CFrequency &f)
             {
                 double fr = f.valueRounded(PhysicalQuantities::CFrequencyUnit::kHz(), 3);
                 return fr >= 190.0 && fr <= 1750.0;
@@ -58,7 +58,7 @@ namespace BlackMisc
             }
 
             //! ADF1 unit
-            static CAdfSystem GetAdf1System(PhysicalQuantities::CFrequency activeFrequency, PhysicalQuantities::CFrequency standbyFrequency = CModulator::FrequencyNotSet())
+            static CAdfSystem GetAdf1System(const PhysicalQuantities::CFrequency &activeFrequency, const PhysicalQuantities::CFrequency &standbyFrequency = CModulator::FrequencyNotSet())
             {
                 return CAdfSystem(CModulator::NameCom1(), activeFrequency, standbyFrequency ==  CModulator::FrequencyNotSet() ? activeFrequency : standbyFrequency);
             }
@@ -70,7 +70,7 @@ namespace BlackMisc
             }
 
             //! ADF2 unit
-            static CAdfSystem GetAdf2System(PhysicalQuantities::CFrequency activeFrequency, PhysicalQuantities::CFrequency standbyFrequency = CModulator::FrequencyNotSet())
+            static CAdfSystem GetAdf2System(const PhysicalQuantities::CFrequency &activeFrequency, const PhysicalQuantities::CFrequency &standbyFrequency = CModulator::FrequencyNotSet())
             {
                 return CAdfSystem(CModulator::NameCom2(), activeFrequency, standbyFrequency ==  CModulator::FrequencyNotSet() ? activeFrequency : standbyFrequency);
             }
diff --git a/src/blackmisc/aviation/aircrafticaocodelist.cpp b/src/blackmisc/aviation/aircrafticaocodelist.cpp
index ee87964ac..8a04afee1 100644
--- a/src/blackmisc/aviation/aircrafticaocodelist.cpp
+++ b/src/blackmisc/aviation/aircrafticaocodelist.cpp
@@ -320,7 +320,7 @@ namespace BlackMisc
             CAircraftIcaoCodeList grouped;
             QString designator;
             QString manufacturer;
-            for (const CAircraftIcaoCode code : as_const(copy))
+            for (const CAircraftIcaoCode &code : as_const(copy))
             {
                 if (code.getDesignator() != designator ||  code.getManufacturer() != manufacturer)
                 {
diff --git a/src/blackmisc/aviation/airlineicaocode.cpp b/src/blackmisc/aviation/airlineicaocode.cpp
index 92f45b0a2..9c2e4c708 100644
--- a/src/blackmisc/aviation/airlineicaocode.cpp
+++ b/src/blackmisc/aviation/airlineicaocode.cpp
@@ -338,7 +338,7 @@ namespace BlackMisc
             return valid;
         }
 
-        QString CAirlineIcaoCode::normalizeDesignator(const QString candidate)
+        QString CAirlineIcaoCode::normalizeDesignator(const QString &candidate)
         {
             QString n(candidate.trimmed().toUpper());
             n = n.left(indexOfChar(n, [](QChar c) { return c.isSpace(); }));
diff --git a/src/blackmisc/aviation/airlineicaocode.h b/src/blackmisc/aviation/airlineicaocode.h
index 7a9beaa4a..71153b876 100644
--- a/src/blackmisc/aviation/airlineicaocode.h
+++ b/src/blackmisc/aviation/airlineicaocode.h
@@ -231,7 +231,7 @@ namespace BlackMisc
             static QSet<QString> specialValidDesignators();
 
             //! Normalize string as airline designator
-            static QString normalizeDesignator(const QString candidate);
+            static QString normalizeDesignator(const QString &candidate);
 
             //! From our DB JSON
             static CAirlineIcaoCode fromDatabaseJson(const QJsonObject &json, const QString &prefix = QString());
diff --git a/src/blackmisc/aviation/altitude.h b/src/blackmisc/aviation/altitude.h
index 9b50cf9d0..350021ffe 100644
--- a/src/blackmisc/aviation/altitude.h
+++ b/src/blackmisc/aviation/altitude.h
@@ -85,7 +85,7 @@ namespace BlackMisc
             CAltitude(const QString &altitudeAsString, BlackMisc::PhysicalQuantities::CPqString::SeparatorMode mode = BlackMisc::PhysicalQuantities::CPqString::SeparatorsLocale);
 
             //! Constructor by CLength
-            CAltitude(BlackMisc::PhysicalQuantities::CLength altitude, ReferenceDatum datum) : CLength(altitude), m_datum(datum) {}
+            CAltitude(const BlackMisc::PhysicalQuantities::CLength &altitude, ReferenceDatum datum) : CLength(altitude), m_datum(datum) {}
 
             //! AGL Above ground level?
             bool isAboveGroundLevel() const { return AboveGround == this->m_datum; }
diff --git a/src/blackmisc/aviation/comsystem.cpp b/src/blackmisc/aviation/comsystem.cpp
index e7a0695c8..f93b01dc3 100644
--- a/src/blackmisc/aviation/comsystem.cpp
+++ b/src/blackmisc/aviation/comsystem.cpp
@@ -94,7 +94,7 @@ namespace BlackMisc
             return CComSystem(CModulator::NameCom1(), BlackMisc::PhysicalQuantities::CFrequency(activeFrequencyMHz, BlackMisc::PhysicalQuantities::CFrequencyUnit::MHz()), BlackMisc::PhysicalQuantities::CFrequency(standbyFrequencyMHz < 0 ? activeFrequencyMHz : standbyFrequencyMHz, BlackMisc::PhysicalQuantities::CFrequencyUnit::MHz()));
         }
 
-        CComSystem CComSystem::getCom1System(CFrequency activeFrequency, CFrequency standbyFrequency)
+        CComSystem CComSystem::getCom1System(const CFrequency &activeFrequency, const CFrequency &standbyFrequency)
         {
             return CComSystem(CModulator::NameCom1(), activeFrequency, standbyFrequency == CModulator::FrequencyNotSet() ? activeFrequency : standbyFrequency);
         }
@@ -104,7 +104,7 @@ namespace BlackMisc
             return CComSystem(CModulator::NameCom2(), BlackMisc::PhysicalQuantities::CFrequency(activeFrequencyMHz, BlackMisc::PhysicalQuantities::CFrequencyUnit::MHz()), BlackMisc::PhysicalQuantities::CFrequency(standbyFrequencyMHz < 0 ? activeFrequencyMHz : standbyFrequencyMHz, BlackMisc::PhysicalQuantities::CFrequencyUnit::MHz()));
         }
 
-        CComSystem CComSystem::getCom2System(CFrequency activeFrequency, CFrequency standbyFrequency)
+        CComSystem CComSystem::getCom2System(const CFrequency &activeFrequency, const CFrequency &standbyFrequency)
         {
             return CComSystem(CModulator::NameCom2(), activeFrequency, standbyFrequency ==  CModulator::FrequencyNotSet() ? activeFrequency : standbyFrequency);
         }
diff --git a/src/blackmisc/aviation/comsystem.h b/src/blackmisc/aviation/comsystem.h
index d0662578d..014160c4a 100644
--- a/src/blackmisc/aviation/comsystem.h
+++ b/src/blackmisc/aviation/comsystem.h
@@ -103,13 +103,13 @@ namespace BlackMisc
             static CComSystem getCom1System(double activeFrequencyMHz, double standbyFrequencyMHz = -1);
 
             //! COM1 unit
-            static CComSystem getCom1System(BlackMisc::PhysicalQuantities::CFrequency activeFrequency, BlackMisc::PhysicalQuantities::CFrequency standbyFrequency = CModulator::FrequencyNotSet());
+            static CComSystem getCom1System(const BlackMisc::PhysicalQuantities::CFrequency &activeFrequency, const BlackMisc::PhysicalQuantities::CFrequency &standbyFrequency = CModulator::FrequencyNotSet());
 
             //! COM2 unit
             static CComSystem getCom2System(double activeFrequencyMHz, double standbyFrequencyMHz = -1);
 
             //! COM2 unit
-            static CComSystem getCom2System(BlackMisc::PhysicalQuantities::CFrequency activeFrequency, BlackMisc::PhysicalQuantities::CFrequency standbyFrequency = CModulator::FrequencyNotSet());
+            static CComSystem getCom2System(const BlackMisc::PhysicalQuantities::CFrequency &activeFrequency, const BlackMisc::PhysicalQuantities::CFrequency &standbyFrequency = CModulator::FrequencyNotSet());
 
             //! Valid civil aviation frequency?
             static bool isValidCivilAviationFrequency(const BlackMisc::PhysicalQuantities::CFrequency &f);
diff --git a/src/blackmisc/aviation/flightplan.cpp b/src/blackmisc/aviation/flightplan.cpp
index f80b1f05a..803b4b8d3 100644
--- a/src/blackmisc/aviation/flightplan.cpp
+++ b/src/blackmisc/aviation/flightplan.cpp
@@ -18,7 +18,7 @@ namespace BlackMisc
     {
         CFlightPlan::CFlightPlan() { }
 
-        CFlightPlan::CFlightPlan(const QString &equipmentIcao, const CAirportIcaoCode &originAirportIcao, const CAirportIcaoCode &destinationAirportIcao, const CAirportIcaoCode &alternateAirportIcao, QDateTime takeoffTimePlanned, QDateTime takeoffTimeActual, const PhysicalQuantities::CTime &enrouteTime, const PhysicalQuantities::CTime &fuelTime, const CAltitude &cruiseAltitude, const PhysicalQuantities::CSpeed &cruiseTrueAirspeed, CFlightPlan::FlightRules flightRules, const QString &route, const QString &remarks)
+        CFlightPlan::CFlightPlan(const QString &equipmentIcao, const CAirportIcaoCode &originAirportIcao, const CAirportIcaoCode &destinationAirportIcao, const CAirportIcaoCode &alternateAirportIcao, const QDateTime &takeoffTimePlanned, const QDateTime &takeoffTimeActual, const PhysicalQuantities::CTime &enrouteTime, const PhysicalQuantities::CTime &fuelTime, const CAltitude &cruiseAltitude, const PhysicalQuantities::CSpeed &cruiseTrueAirspeed, CFlightPlan::FlightRules flightRules, const QString &route, const QString &remarks)
             : m_equipmentIcao(equipmentIcao), m_originAirportIcao(originAirportIcao), m_destinationAirportIcao(destinationAirportIcao), m_alternateAirportIcao(alternateAirportIcao),
               m_takeoffTimePlanned(takeoffTimePlanned), m_takeoffTimeActual(takeoffTimeActual), m_enrouteTime(enrouteTime), m_fuelTime(fuelTime),
               m_cruiseAltitude(cruiseAltitude), m_cruiseTrueAirspeed(cruiseTrueAirspeed), m_flightRules(flightRules),
diff --git a/src/blackmisc/aviation/flightplan.h b/src/blackmisc/aviation/flightplan.h
index 6d5dd1862..94025d0c9 100644
--- a/src/blackmisc/aviation/flightplan.h
+++ b/src/blackmisc/aviation/flightplan.h
@@ -53,7 +53,7 @@ namespace BlackMisc
 
             //! Constructor
             CFlightPlan(const QString &equipmentIcao, const CAirportIcaoCode &originAirportIcao, const CAirportIcaoCode &destinationAirportIcao, const CAirportIcaoCode &alternateAirportIcao,
-                        QDateTime takeoffTimePlanned, QDateTime takeoffTimeActual, const PhysicalQuantities::CTime &enrouteTime, const PhysicalQuantities::CTime &fuelTime,
+                        const QDateTime &takeoffTimePlanned, const QDateTime &takeoffTimeActual, const PhysicalQuantities::CTime &enrouteTime, const PhysicalQuantities::CTime &fuelTime,
                         const CAltitude &cruiseAltitude, const PhysicalQuantities::CSpeed &cruiseTrueAirspeed, FlightRules flightRules, const QString &route, const QString &remarks);
 
             //! Set ICAO aircraft equipment code string (e.g. "T/A320/F")
@@ -78,16 +78,16 @@ namespace BlackMisc
             void setAlternateAirportIcao(const CAirportIcaoCode &alternateAirportIcao) { m_alternateAirportIcao = alternateAirportIcao; }
 
             //! Set planned takeoff time
-            void setTakeoffTimePlanned(QDateTime takeoffTimePlanned) { m_takeoffTimePlanned = takeoffTimePlanned; }
+            void setTakeoffTimePlanned(const QDateTime &takeoffTimePlanned) { m_takeoffTimePlanned = takeoffTimePlanned; }
 
             //! Set planned takeoff time hh:mm
-            void setTakeoffTimePlanned(QString time) { m_takeoffTimePlanned = QDateTime::currentDateTimeUtc(); m_takeoffTimePlanned.setTime(QTime::fromString(time, "hh:mm"));}
+            void setTakeoffTimePlanned(const QString &time) { m_takeoffTimePlanned = QDateTime::currentDateTimeUtc(); m_takeoffTimePlanned.setTime(QTime::fromString(time, "hh:mm"));}
 
             //! Set actual takeoff time (reserved for ATC use)
-            void setTakeoffTimeActual(QDateTime takeoffTimeActual) { m_takeoffTimeActual = takeoffTimeActual; }
+            void setTakeoffTimeActual(const QDateTime &takeoffTimeActual) { m_takeoffTimeActual = takeoffTimeActual; }
 
             //! Set actual takeoff time hh:mm
-            void setTakeoffTimeActual(QString time) { m_takeoffTimeActual = QDateTime::currentDateTimeUtc(); m_takeoffTimeActual.setTime(QTime::fromString(time, "hh:mm"));}
+            void setTakeoffTimeActual(const QString &time) { m_takeoffTimeActual = QDateTime::currentDateTimeUtc(); m_takeoffTimeActual.setTime(QTime::fromString(time, "hh:mm"));}
 
             //! Set planned enroute flight time
             void setEnrouteTime(const PhysicalQuantities::CTime &enrouteTime) { m_enrouteTime = enrouteTime; m_enrouteTime.switchUnit(BlackMisc::PhysicalQuantities::CTimeUnit::hrmin());}
diff --git a/src/blackmisc/aviation/heading.h b/src/blackmisc/aviation/heading.h
index c0b648d85..2c7ab5e56 100644
--- a/src/blackmisc/aviation/heading.h
+++ b/src/blackmisc/aviation/heading.h
@@ -74,7 +74,7 @@ namespace BlackMisc
             CHeading(double value, ReferenceNorth north, const BlackMisc::PhysicalQuantities::CAngleUnit &unit) : CAngle(value, unit), m_north(north) {}
 
             //! \brief Constructor by CAngle
-            CHeading(CAngle heading, ReferenceNorth north) : CAngle(heading), m_north(north) {}
+            CHeading(const CAngle &heading, ReferenceNorth north) : CAngle(heading), m_north(north) {}
 
             //! \brief Magnetic heading?
             bool isMagneticHeading() const { return Magnetic == this->m_north; }
diff --git a/src/blackmisc/aviation/navsystem.h b/src/blackmisc/aviation/navsystem.h
index 76ebff70a..32a52e543 100644
--- a/src/blackmisc/aviation/navsystem.h
+++ b/src/blackmisc/aviation/navsystem.h
@@ -55,14 +55,14 @@ namespace BlackMisc
             }
 
             //! Valid civil aviation frequency?
-            static bool isValidCivilNavigationFrequency(BlackMisc::PhysicalQuantities::CFrequency f)
+            static bool isValidCivilNavigationFrequency(const BlackMisc::PhysicalQuantities::CFrequency &f)
             {
                 double fr = f.valueRounded(BlackMisc::PhysicalQuantities::CFrequencyUnit::MHz(), 3);
                 return fr >= 108.0 && fr <= 117.95;
             }
 
             //! Valid military aviation frequency?
-            static bool isValidMilitaryNavigationFrequency(BlackMisc::PhysicalQuantities::CFrequency f)
+            static bool isValidMilitaryNavigationFrequency(const BlackMisc::PhysicalQuantities::CFrequency &f)
             {
                 double fr = f.valueRounded(BlackMisc::PhysicalQuantities::CFrequencyUnit::MHz(), 3);
                 return fr >= 960.0 && fr <= 1215.0; // valid TACAN frequency
@@ -75,7 +75,7 @@ namespace BlackMisc
             }
 
             //! NAV1 unit
-            static CNavSystem getNav1System(BlackMisc::PhysicalQuantities::CFrequency activeFrequency, BlackMisc::PhysicalQuantities::CFrequency standbyFrequency = CModulator::FrequencyNotSet())
+            static CNavSystem getNav1System(const BlackMisc::PhysicalQuantities::CFrequency &activeFrequency, const BlackMisc::PhysicalQuantities::CFrequency &standbyFrequency = CModulator::FrequencyNotSet())
             {
                 return CNavSystem(CModulator::NameNav1(), activeFrequency, standbyFrequency ==  CModulator::FrequencyNotSet() ? activeFrequency : standbyFrequency);
             }
@@ -87,7 +87,7 @@ namespace BlackMisc
             }
 
             //! NAV2 unit
-            static CNavSystem getNav2System(BlackMisc::PhysicalQuantities::CFrequency activeFrequency, BlackMisc::PhysicalQuantities::CFrequency standbyFrequency = CModulator::FrequencyNotSet())
+            static CNavSystem getNav2System(const BlackMisc::PhysicalQuantities::CFrequency &activeFrequency, const BlackMisc::PhysicalQuantities::CFrequency &standbyFrequency = CModulator::FrequencyNotSet())
             {
                 return CNavSystem(CModulator::NameNav2(), activeFrequency, standbyFrequency ==  CModulator::FrequencyNotSet() ? activeFrequency : standbyFrequency);
             }
diff --git a/src/blackmisc/aviation/track.h b/src/blackmisc/aviation/track.h
index 6bae2035b..51c81cdb1 100644
--- a/src/blackmisc/aviation/track.h
+++ b/src/blackmisc/aviation/track.h
@@ -75,7 +75,7 @@ namespace BlackMisc
             CTrack(double value, ReferenceNorth north, const BlackMisc::PhysicalQuantities::CAngleUnit &unit) : CAngle(value, unit), m_north(north) {}
 
             //! \brief Constructor by CAngle
-            CTrack(BlackMisc::PhysicalQuantities::CAngle track, ReferenceNorth north) : CAngle(track), m_north(north) {}
+            CTrack(const BlackMisc::PhysicalQuantities::CAngle &track, ReferenceNorth north) : CAngle(track), m_north(north) {}
 
             //! \brief Magnetic Track?
             bool isMagneticTrack() const
diff --git a/src/blackmisc/aviation/transponder.cpp b/src/blackmisc/aviation/transponder.cpp
index c57a8d188..8857d7a40 100644
--- a/src/blackmisc/aviation/transponder.cpp
+++ b/src/blackmisc/aviation/transponder.cpp
@@ -29,13 +29,13 @@ namespace BlackMisc
             m_transponderCode(transponderCode), m_transponderMode(transponderMode)
         {  }
 
-        CTransponder::CTransponder(int transponderCode, QString transponderMode) :
+        CTransponder::CTransponder(int transponderCode, const QString &transponderMode) :
             m_transponderCode(transponderCode), m_transponderMode(StateStandby)
         {
             this->setModeAsString(transponderMode);
         }
 
-        CTransponder::CTransponder(QString transponderCode, CTransponder::TransponderMode transponderMode) :
+        CTransponder::CTransponder(const QString &transponderCode, CTransponder::TransponderMode transponderMode) :
             m_transponderCode(0), m_transponderMode(transponderMode)
         {
             bool ok = false;
@@ -43,7 +43,7 @@ namespace BlackMisc
             if (!ok) this->m_transponderCode = -1; // will cause assert / exception
         }
 
-        CTransponder::CTransponder(QString transponderCode, QString transponderMode) :
+        CTransponder::CTransponder(const QString &transponderCode, const QString &transponderMode) :
             m_transponderCode(0), m_transponderMode(StateStandby)
         {
             bool ok = false;
diff --git a/src/blackmisc/aviation/transponder.h b/src/blackmisc/aviation/transponder.h
index 14c6a52ec..acad7f314 100644
--- a/src/blackmisc/aviation/transponder.h
+++ b/src/blackmisc/aviation/transponder.h
@@ -64,13 +64,13 @@ namespace BlackMisc
             CTransponder(int transponderCode, TransponderMode transponderMode);
 
             //! Constructor with transponder mode as string
-            CTransponder(int transponderCode, QString transponderMode);
+            CTransponder(int transponderCode, const QString &transponderMode);
 
             //! Constructor, code as string
-            CTransponder(QString transponderCode, TransponderMode transponderMode);
+            CTransponder(const QString &transponderCode, TransponderMode transponderMode);
 
             //! Constructor
-            CTransponder(QString transponderCode, QString transponderMode);
+            CTransponder(const QString &transponderCode, const QString &transponderMode);
 
             //! Are set values valid?
             bool validValues() const;
diff --git a/src/blackmisc/compare.h b/src/blackmisc/compare.h
index 0f0e44f80..a9d80c51c 100644
--- a/src/blackmisc/compare.h
+++ b/src/blackmisc/compare.h
@@ -207,7 +207,7 @@ namespace BlackMisc
 
         //! Recurse into one of the submembers of T, comparing members of that member.
         template <typename T, std::enable_if_t<THasMetaClass<T>::value, int> = 0>
-        QList<QPair<QString, bool>> operator ()(const T &a, const T &b, QStringList memberNames) const
+        QList<QPair<QString, bool>> operator ()(const T &a, const T &b, QStringList memberNames) const // clazy:exclude=function-args-by-ref
         {
             if (memberNames.isEmpty()) { return CMetaMemberComparator()(a, b); }
             auto meta = introspect<T>().without(MetaFlags<DisabledForComparison>());
@@ -227,7 +227,7 @@ namespace BlackMisc
 
         //! Return empty list if T doesn't have a metaclass.
         template <typename T, std::enable_if_t<!THasMetaClass<T>::value, int> = 0>
-        QList<QPair<QString, bool>> operator ()(const T &, const T &, QStringList) const { return {}; }
+        QList<QPair<QString, bool>> operator ()(const T &, const T &, QStringList) const { return {}; } // clazy:exclude=function-args-by-ref
 
     private:
         template <typename T> static auto baseEquals(const T *a, const T *b) { return CMetaMemberComparator()(*a, *b); }
diff --git a/src/blackmisc/directoryutils.cpp b/src/blackmisc/directoryutils.cpp
index bd383b54c..34368a04f 100644
--- a/src/blackmisc/directoryutils.cpp
+++ b/src/blackmisc/directoryutils.cpp
@@ -202,7 +202,7 @@ namespace BlackMisc
             const QStringList relativeSubdirs = CDirectoryUtils::getSubDirectories(dirSource);
             if (!relativeSubdirs.isEmpty())
             {
-                for (const QString relativeSubdir : relativeSubdirs)
+                for (const QString &relativeSubdir : relativeSubdirs)
                 {
                     const QString sourceSubdir = CFileUtils::appendFilePaths(dirSource, relativeSubdir);
                     const QString targetSubdir = CFileUtils::appendFilePaths(dirTarget, relativeSubdir);
diff --git a/src/blackmisc/genericdbusinterface.h b/src/blackmisc/genericdbusinterface.h
index 517575ce3..fe6e57fc0 100644
--- a/src/blackmisc/genericdbusinterface.h
+++ b/src/blackmisc/genericdbusinterface.h
@@ -64,7 +64,7 @@ namespace BlackMisc
 
         //! Call DBus, no return value
         template <typename... Args>
-        void callDBus(const QLatin1String &method, Args&&... args)
+        void callDBus(QLatin1String method, Args&&... args)
         {
             QList<QVariant> argumentList { QVariant::fromValue(std::forward<Args>(args))... };
             this->asyncCallWithArgumentList(method, argumentList);
@@ -72,7 +72,7 @@ namespace BlackMisc
 
         //! Call DBus with synchronous return value
         template <typename Ret, typename... Args>
-        Ret callDBusRet(const QLatin1String &method, Args&&... args)
+        Ret callDBusRet(QLatin1String method, Args&&... args)
         {
             QList<QVariant> argumentList { QVariant::fromValue(std::forward<Args>(args))... };
             QDBusPendingReply<Ret> pr = this->asyncCallWithArgumentList(method, argumentList);
@@ -82,7 +82,7 @@ namespace BlackMisc
         //! Call DBus with asynchronous return value
         //! Callback can be any callable object taking a single argument of type QDBusPendingCallWatcher*.
         template <typename Func, typename... Args>
-        void callDBusAsync(const QLatin1String &method, Func callback, Args&&... args)
+        void callDBusAsync(QLatin1String method, Func callback, Args&&... args)
         {
             QList<QVariant> argumentList { QVariant::fromValue(std::forward<Args>(args))... };
             QDBusPendingCall pc = this->asyncCallWithArgumentList(method, argumentList);
diff --git a/src/blackmisc/icons.cpp b/src/blackmisc/icons.cpp
index 4e953e4dd..5fb62a62b 100644
--- a/src/blackmisc/icons.cpp
+++ b/src/blackmisc/icons.cpp
@@ -353,7 +353,7 @@ namespace BlackMisc
         return pm;
     }
 
-    QPixmap transparentPixmapImpl(const QSize &size)
+    QPixmap transparentPixmapImpl(QSize size)
     {
         // http://curtis.humphreyonline.us/code/qt-code/making-a-qpixmap-transparent-wrong-way-right-way
         QPixmap pix(size);
@@ -1195,7 +1195,7 @@ namespace BlackMisc
         return QPixmap::fromImage(destBackgroundImg);
     }
 
-    QIcon CIcons::changeIconBackgroundColor(const QIcon &icon, Qt::GlobalColor backgroundColor, const QSize &targetsize)
+    QIcon CIcons::changeIconBackgroundColor(const QIcon &icon, Qt::GlobalColor backgroundColor, QSize targetsize)
     {
         QImage imgSource(icon.pixmap(targetsize).toImage());
         QImage destBackgroundImg(changeImageBackgroundColor(imgSource, backgroundColor));
diff --git a/src/blackmisc/icons.h b/src/blackmisc/icons.h
index 582947f05..49223154e 100644
--- a/src/blackmisc/icons.h
+++ b/src/blackmisc/icons.h
@@ -694,7 +694,7 @@ namespace BlackMisc
         static QPixmap changeResourceBackgroundColor(const QString &resource, Qt::GlobalColor backgroundColor);
 
         //! Change color of icon
-        static QIcon changeIconBackgroundColor(const QIcon &icon, Qt::GlobalColor backgroundColor, const QSize &targetsize);
+        static QIcon changeIconBackgroundColor(const QIcon &icon, Qt::GlobalColor backgroundColor, QSize targetsize);
 
         //! Change image background color
         static QImage changeImageBackgroundColor(const QImage &imgSource, Qt::GlobalColor backgroundColor);
diff --git a/src/blackmisc/input/hotkeycombination.cpp b/src/blackmisc/input/hotkeycombination.cpp
index 8f5fa3db7..8651a81fc 100644
--- a/src/blackmisc/input/hotkeycombination.cpp
+++ b/src/blackmisc/input/hotkeycombination.cpp
@@ -20,27 +20,27 @@ namespace BlackMisc
 {
     namespace Input
     {
-        CHotkeyCombination::CHotkeyCombination(const CKeyboardKey &key) : CHotkeyCombination(CKeyboardKeyList(key))
+        CHotkeyCombination::CHotkeyCombination(CKeyboardKey key) : CHotkeyCombination(CKeyboardKeyList(key))
         { }
 
         CHotkeyCombination::CHotkeyCombination(const CKeyboardKeyList &keys) : m_keyboardKeys(keys)
         { }
 
-        void CHotkeyCombination::addKeyboardKey(const CKeyboardKey &key)
+        void CHotkeyCombination::addKeyboardKey(CKeyboardKey key)
         {
             if (m_keyboardKeys.contains(key)) { return; }
             m_keyboardKeys.push_back(key);
             m_keyboardKeys.sortBy(&CKeyboardKey::getKey);
         }
 
-        void CHotkeyCombination::addJoystickButton(const CJoystickButton &button)
+        void CHotkeyCombination::addJoystickButton(CJoystickButton button)
         {
             if (m_joystickButtons.contains(button)) { return; }
             m_joystickButtons.push_back(button);
             m_joystickButtons.sortBy(&CJoystickButton::getButtonIndex);
         }
 
-        void CHotkeyCombination::replaceKey(const CKeyboardKey &oldKey, const CKeyboardKey &newKey)
+        void CHotkeyCombination::replaceKey(CKeyboardKey oldKey, CKeyboardKey newKey)
         {
             Q_ASSERT(!oldKey.isUnknown());
             m_keyboardKeys.remove(oldKey);
@@ -48,19 +48,19 @@ namespace BlackMisc
             m_keyboardKeys.sortBy(&CKeyboardKey::getKey);
         }
 
-        void CHotkeyCombination::replaceButton(const CJoystickButton &oldButton, const CJoystickButton &newButton)
+        void CHotkeyCombination::replaceButton(CJoystickButton oldButton, CJoystickButton newButton)
         {
             m_joystickButtons.remove(oldButton);
             if (newButton.isValid()) { m_joystickButtons.push_back(newButton); }
             m_joystickButtons.sortBy(&CJoystickButton::getButtonIndex);
         }
 
-        void CHotkeyCombination::removeKeyboardKey(const CKeyboardKey &key)
+        void CHotkeyCombination::removeKeyboardKey(CKeyboardKey key)
         {
             replaceKey(key, CKeyboardKey());
         }
 
-        void CHotkeyCombination::removeJoystickButton(const CJoystickButton &button)
+        void CHotkeyCombination::removeJoystickButton(CJoystickButton button)
         {
             replaceButton(button, CJoystickButton());
         }
@@ -75,6 +75,7 @@ namespace BlackMisc
         {
             Q_UNUSED(i18n);
             QStringList sl;
+            sl.reserve(m_keyboardKeys.size() + m_joystickButtons.size());
             for (const auto &key : m_keyboardKeys)
             {
                 sl << key.toQString();
diff --git a/src/blackmisc/input/hotkeycombination.h b/src/blackmisc/input/hotkeycombination.h
index 56b55c779..940b12512 100644
--- a/src/blackmisc/input/hotkeycombination.h
+++ b/src/blackmisc/input/hotkeycombination.h
@@ -35,7 +35,7 @@ namespace BlackMisc
             CHotkeyCombination() = default;
 
             //! Init with key
-            CHotkeyCombination(const CKeyboardKey &key);
+            CHotkeyCombination(CKeyboardKey key);
 
             //! Init with list of keys
             CHotkeyCombination(const CKeyboardKeyList &keys);
@@ -53,22 +53,22 @@ namespace BlackMisc
             CJoystickButtonList getJoystickButtons() const { return m_joystickButtons; }
 
             //! Add keyboard key
-            void addKeyboardKey(const CKeyboardKey &key);
+            void addKeyboardKey(CKeyboardKey key);
 
             //! Add joystick button
-            void addJoystickButton(const CJoystickButton &button);
+            void addJoystickButton(CJoystickButton button);
 
             //! Replace oldKey with newKey
-            void replaceKey(const CKeyboardKey &oldKey, const CKeyboardKey &newKey);
+            void replaceKey(CKeyboardKey oldKey, CKeyboardKey newKey);
 
             //! Replace oldButton with newButton
-            void replaceButton(const CJoystickButton &oldButton, const CJoystickButton &newButton);
+            void replaceButton(CJoystickButton oldButton, CJoystickButton newButton);
 
             //! Remove keyboard key
-            void removeKeyboardKey(const CKeyboardKey &key);
+            void removeKeyboardKey(CKeyboardKey key);
 
             //! Remove joystick button
-            void removeJoystickButton(const CJoystickButton &button);
+            void removeJoystickButton(CJoystickButton button);
 
             //! Is sequence empty?
             bool isEmpty() const { return m_keyboardKeys.isEmpty() && m_joystickButtons.isEmpty(); }
diff --git a/src/blackmisc/input/joystickbutton.cpp b/src/blackmisc/input/joystickbutton.cpp
index 4aee8c8de..166ec04df 100644
--- a/src/blackmisc/input/joystickbutton.cpp
+++ b/src/blackmisc/input/joystickbutton.cpp
@@ -24,7 +24,7 @@ namespace BlackMisc
             m_buttonIndex = buttonIndex;
         }
 
-        void CJoystickButton::setButtonObject(const CJoystickButton &button)
+        void CJoystickButton::setButtonObject(CJoystickButton button)
         {
             this->m_buttonIndex = button.m_buttonIndex;
         }
diff --git a/src/blackmisc/input/joystickbutton.h b/src/blackmisc/input/joystickbutton.h
index 1aacd276a..602c1927a 100644
--- a/src/blackmisc/input/joystickbutton.h
+++ b/src/blackmisc/input/joystickbutton.h
@@ -57,7 +57,7 @@ namespace BlackMisc
             bool isValid() const { return m_buttonIndex >= 0 ? true : false; }
 
             //! Set button object
-            void setButtonObject(const CJoystickButton &button);
+            void setButtonObject(CJoystickButton button);
 
             //! \copydoc BlackMisc::Mixin::Index::setPropertyByIndex
             void setPropertyByIndex(const BlackMisc::CPropertyIndex &index, const CVariant &variant);
diff --git a/src/blackmisc/input/keyboardkey.cpp b/src/blackmisc/input/keyboardkey.cpp
index f3b5f25c3..9b0218613 100644
--- a/src/blackmisc/input/keyboardkey.cpp
+++ b/src/blackmisc/input/keyboardkey.cpp
@@ -34,7 +34,7 @@ namespace BlackMisc
             return getKeyAsString();
         }
 
-        void CKeyboardKey::setKeyObject(const CKeyboardKey &key)
+        void CKeyboardKey::setKeyObject(CKeyboardKey key)
         {
             this->m_keyCode = key.m_keyCode;
         }
diff --git a/src/blackmisc/input/keyboardkey.h b/src/blackmisc/input/keyboardkey.h
index 2372bef61..155ec82cc 100644
--- a/src/blackmisc/input/keyboardkey.h
+++ b/src/blackmisc/input/keyboardkey.h
@@ -52,7 +52,7 @@ namespace BlackMisc
             QString getKeyAsString() const;
 
             //! Set key code
-            void setKey(const KeyCode key) { this->m_keyCode = key; }
+            void setKey(KeyCode key) { this->m_keyCode = key; }
 
             //! Set key code
             void setKey(int key) { this->m_keyCode = static_cast<KeyCode>(key); }
@@ -76,7 +76,7 @@ namespace BlackMisc
             }
 
             //! Set key object
-            void setKeyObject(const CKeyboardKey &key);
+            void setKeyObject(CKeyboardKey key);
 
             //! \copydoc BlackMisc::Mixin::Index::setPropertyByIndex
             void setPropertyByIndex(const BlackMisc::CPropertyIndex &index, const CVariant &variant);
diff --git a/src/blackmisc/input/keyboardkeylist.cpp b/src/blackmisc/input/keyboardkeylist.cpp
index 50b125832..8ceaaadcc 100644
--- a/src/blackmisc/input/keyboardkeylist.cpp
+++ b/src/blackmisc/input/keyboardkeylist.cpp
@@ -16,7 +16,7 @@ namespace BlackMisc
     {
         CKeyboardKeyList::CKeyboardKeyList() { }
 
-        CKeyboardKeyList::CKeyboardKeyList(const CKeyboardKey &key)
+        CKeyboardKeyList::CKeyboardKeyList(CKeyboardKey key)
         {
             this->push_back(key);
         }
diff --git a/src/blackmisc/input/keyboardkeylist.h b/src/blackmisc/input/keyboardkeylist.h
index d8d230c73..942f5c42a 100644
--- a/src/blackmisc/input/keyboardkeylist.h
+++ b/src/blackmisc/input/keyboardkeylist.h
@@ -38,7 +38,7 @@ namespace BlackMisc
             CKeyboardKeyList();
 
             //! Init by single key
-            CKeyboardKeyList(const CKeyboardKey &key);
+            CKeyboardKeyList(CKeyboardKey key);
 
             //! Construct from a base class object.
             CKeyboardKeyList(const CSequence<CKeyboardKey> &baseClass);
diff --git a/src/blackmisc/json.cpp b/src/blackmisc/json.cpp
index bc052cf63..07ba3aa37 100644
--- a/src/blackmisc/json.cpp
+++ b/src/blackmisc/json.cpp
@@ -92,74 +92,74 @@ const QJsonValue &operator >>(const QJsonValue &json, QByteArray &value)
     return json;
 }
 
-const QJsonValueRef &operator >>(const QJsonValueRef &json, int &value)
+QJsonValueRef operator >>(QJsonValueRef json, int &value)
 {
     value = json.toInt();
     return json;
 }
 
-const QJsonValueRef &operator >>(const QJsonValueRef &json, qlonglong &value)
+QJsonValueRef operator >>(QJsonValueRef json, qlonglong &value)
 {
     value = static_cast<qlonglong>(json.toDouble());
     return json;
 }
 
-const QJsonValueRef &operator >>(const QJsonValueRef &json, qulonglong &value)
+QJsonValueRef operator >>(QJsonValueRef json, qulonglong &value)
 {
     value = static_cast<qulonglong>(json.toDouble());
     return json;
 }
 
-const QJsonValueRef &operator >>(const QJsonValueRef &json, uint &value)
+QJsonValueRef operator >>(QJsonValueRef json, uint &value)
 {
     value = static_cast<uint>(json.toInt());
     return json;
 }
 
-const QJsonValueRef &operator >>(const QJsonValueRef &json, qint16 &value)
+QJsonValueRef operator >>(QJsonValueRef json, qint16 &value)
 {
     value = static_cast<qint16>(json.toInt());
     return json;
 }
 
-const QJsonValueRef &operator >>(const QJsonValueRef &json, QString &value)
+QJsonValueRef operator >>(QJsonValueRef json, QString &value)
 {
     value = json.toString();
     return json;
 }
 
-const QJsonValueRef &operator >>(const QJsonValueRef &json, QStringList &value)
+QJsonValueRef operator >>(QJsonValueRef json, QStringList &value)
 {
     for (auto && element : json.toArray()) { value << element.toString(); }
     return json;
 }
 
-const QJsonValueRef &operator >>(const QJsonValueRef &json, double &value)
+QJsonValueRef operator >>(QJsonValueRef json, double &value)
 {
     value = json.toDouble();
     return json;
 }
 
-const QJsonValueRef &operator >>(const QJsonValueRef &json, bool &value)
+QJsonValueRef operator >>(QJsonValueRef json, bool &value)
 {
     value = json.toBool();
     return json;
 }
 
-const QJsonValueRef &operator >>(const QJsonValueRef &json, QDateTime &value)
+QJsonValueRef operator >>(QJsonValueRef json, QDateTime &value)
 {
     value = QDateTime::fromString(json.toString());
     return json;
 }
 
-const QJsonValueRef &operator >>(const QJsonValueRef &json, QPixmap &value)
+QJsonValueRef operator >>(QJsonValueRef json, QPixmap &value)
 {
     const QString hex(json.toString());
     BlackMisc::pngHexStringToPixmapRef(hex, value);
     return json;
 }
 
-const QJsonValueRef &operator >>(const QJsonValueRef &json, QByteArray &value)
+QJsonValueRef operator >>(QJsonValueRef json, QByteArray &value)
 {
     const QString hex(json.toString());
     value = BlackMisc::byteArrayFromHexString(hex);
diff --git a/src/blackmisc/json.h b/src/blackmisc/json.h
index 07c876b14..c3b6b0e63 100644
--- a/src/blackmisc/json.h
+++ b/src/blackmisc/json.h
@@ -73,18 +73,18 @@ BLACKMISC_EXPORT const QJsonValue &operator >>(const QJsonValue &json, bool &val
 BLACKMISC_EXPORT const QJsonValue &operator >>(const QJsonValue &json, QDateTime &value);
 BLACKMISC_EXPORT const QJsonValue &operator >>(const QJsonValue &json, QPixmap &value);
 BLACKMISC_EXPORT const QJsonValue &operator >>(const QJsonValue &json, QByteArray &value);
-BLACKMISC_EXPORT const QJsonValueRef &operator >>(const QJsonValueRef &json, int &value);
-BLACKMISC_EXPORT const QJsonValueRef &operator >>(const QJsonValueRef &json, qlonglong &value);
-BLACKMISC_EXPORT const QJsonValueRef &operator >>(const QJsonValueRef &json, qulonglong &value);
-BLACKMISC_EXPORT const QJsonValueRef &operator >>(const QJsonValueRef &json, uint &value);
-BLACKMISC_EXPORT const QJsonValueRef &operator >>(const QJsonValueRef &json, qint16 &value);
-BLACKMISC_EXPORT const QJsonValueRef &operator >>(const QJsonValueRef &json, QString &value);
-BLACKMISC_EXPORT const QJsonValueRef &operator >>(const QJsonValueRef &json, QStringList &value);
-BLACKMISC_EXPORT const QJsonValueRef &operator >>(const QJsonValueRef &json, double &value);
-BLACKMISC_EXPORT const QJsonValueRef &operator >>(const QJsonValueRef &json, bool &value);
-BLACKMISC_EXPORT const QJsonValueRef &operator >>(const QJsonValueRef &json, QDateTime &value);
-BLACKMISC_EXPORT const QJsonValueRef &operator >>(const QJsonValueRef &json, QPixmap &value);
-BLACKMISC_EXPORT const QJsonValueRef &operator >>(const QJsonValueRef &json, QByteArray &value);
+BLACKMISC_EXPORT QJsonValueRef operator >>(QJsonValueRef json, int &value);
+BLACKMISC_EXPORT QJsonValueRef operator >>(QJsonValueRef json, qlonglong &value);
+BLACKMISC_EXPORT QJsonValueRef operator >>(QJsonValueRef json, qulonglong &value);
+BLACKMISC_EXPORT QJsonValueRef operator >>(QJsonValueRef json, uint &value);
+BLACKMISC_EXPORT QJsonValueRef operator >>(QJsonValueRef json, qint16 &value);
+BLACKMISC_EXPORT QJsonValueRef operator >>(QJsonValueRef json, QString &value);
+BLACKMISC_EXPORT QJsonValueRef operator >>(QJsonValueRef json, QStringList &value);
+BLACKMISC_EXPORT QJsonValueRef operator >>(QJsonValueRef json, double &value);
+BLACKMISC_EXPORT QJsonValueRef operator >>(QJsonValueRef json, bool &value);
+BLACKMISC_EXPORT QJsonValueRef operator >>(QJsonValueRef json, QDateTime &value);
+BLACKMISC_EXPORT QJsonValueRef operator >>(QJsonValueRef json, QPixmap &value);
+BLACKMISC_EXPORT QJsonValueRef operator >>(QJsonValueRef json, QByteArray &value);
 
 //! @}
 
@@ -146,9 +146,8 @@ const QJsonValue &operator>>(const QJsonValue &json, QFlags<ENUM> &value)
 
 //! \brief Specialized JSON deserialization for enum
 //! \ingroup JSON
-template<class ENUM>
-std::enable_if_t<std::is_enum<ENUM>::value, QJsonValueRef>
-const &operator>>(const QJsonValueRef &json, ENUM &value)
+template<class ENUM, typename = std::enable_if_t<std::is_enum<ENUM>::value>>
+QJsonValueRef operator>>(QJsonValueRef json, ENUM &value)
 {
     value = static_cast<ENUM>(json.toInt());
     return json;
@@ -157,7 +156,7 @@ const &operator>>(const QJsonValueRef &json, ENUM &value)
 //! \brief Specialized JSON deserialization for QFlags enum
 //! \ingroup JSON
 template<class ENUM>
-const QJsonValueRef &operator>>(const QJsonValueRef &json, QFlags<ENUM> &value)
+QJsonValueRef operator>>(QJsonValueRef json, QFlags<ENUM> &value)
 {
     value = static_cast<QFlags<ENUM>>(json.toInt());
     return json;
@@ -166,7 +165,7 @@ const QJsonValueRef &operator>>(const QJsonValueRef &json, QFlags<ENUM> &value)
 //! \brief Specialized JSON deserialization for pair
 //! \ingroup JSON
 template<class FIRST, class SECOND>
-const QJsonValueRef &operator>>(const QJsonValueRef &json, std::pair<FIRST, SECOND> &pair)
+QJsonValueRef operator>>(QJsonValueRef json, std::pair<FIRST, SECOND> &pair)
 {
     json.toArray() >> pair.first >> pair.second;
     return json;
@@ -308,7 +307,7 @@ namespace BlackMisc
             }
 
             //! operator >> for JSON
-            friend const QJsonValueRef &operator>>(const QJsonValueRef &json, Derived &obj)
+            friend QJsonValueRef operator>>(QJsonValueRef json, Derived &obj)
             {
                 obj.convertFromJson(json.toObject());
                 return json;
diff --git a/src/blackmisc/network/textmessagelist.cpp b/src/blackmisc/network/textmessagelist.cpp
index bcf055242..34739d077 100644
--- a/src/blackmisc/network/textmessagelist.cpp
+++ b/src/blackmisc/network/textmessagelist.cpp
@@ -53,7 +53,7 @@ namespace BlackMisc
         CTextMessageList::CTextMessageList(const QString &message, const QList<CFrequency> &frequencies, const BlackMisc::Aviation::CCallsign &fromCallsign)
         {
             if (frequencies.isEmpty()) return;
-            foreach(CFrequency frequency, frequencies)
+            for (const CFrequency &frequency : frequencies)
             {
                 CTextMessage pm(message, frequency, fromCallsign);
                 this->push_back(pm);
diff --git a/src/blackmisc/network/url.cpp b/src/blackmisc/network/url.cpp
index 677349fba..8c7ef871d 100644
--- a/src/blackmisc/network/url.cpp
+++ b/src/blackmisc/network/url.cpp
@@ -166,7 +166,7 @@ namespace BlackMisc
             return url;
         }
 
-        bool CUrl::pathEndsWith(const QString ending, Qt::CaseSensitivity cs) const
+        bool CUrl::pathEndsWith(const QString &ending, Qt::CaseSensitivity cs) const
         {
             return m_path.endsWith(ending, cs);
         }
@@ -220,7 +220,7 @@ namespace BlackMisc
             return QUrl::fromLocalFile(localFile);
         }
 
-        QString CUrl::stripQueryString(const QString query)
+        QString CUrl::stripQueryString(const QString &query)
         {
             QString q(query.trimmed());
             if (q.startsWith("?") || q.startsWith("&"))
diff --git a/src/blackmisc/network/url.h b/src/blackmisc/network/url.h
index 33a262708..587d4d1f0 100644
--- a/src/blackmisc/network/url.h
+++ b/src/blackmisc/network/url.h
@@ -137,7 +137,7 @@ namespace BlackMisc
             CUrl withSwitchedScheme(const QString &protocol, int port) const;
 
             //! Path ending with?
-            bool pathEndsWith(const QString ending, Qt::CaseSensitivity cs = Qt::CaseInsensitive) const;
+            bool pathEndsWith(const QString &ending, Qt::CaseSensitivity cs = Qt::CaseInsensitive) const;
 
             //! \copydoc BlackMisc::Mixin::Index::propertyByIndex
             CVariant propertyByIndex(const BlackMisc::CPropertyIndex &index) const;
@@ -173,7 +173,7 @@ namespace BlackMisc
             QString m_path;
             QString m_query;
 
-            static QString stripQueryString(const QString query);
+            static QString stripQueryString(const QString &query);
 
             BLACK_METACLASS(
                 CUrl,
diff --git a/src/blackmisc/pq/time.cpp b/src/blackmisc/pq/time.cpp
index 1e4ebef2d..dc279712a 100644
--- a/src/blackmisc/pq/time.cpp
+++ b/src/blackmisc/pq/time.cpp
@@ -38,7 +38,7 @@ namespace BlackMisc
             }
         }
 
-        CTime::CTime(const QTime &time, bool negative) : CPhysicalQuantity(0, CTimeUnit::nullUnit())
+        CTime::CTime(QTime time, bool negative) : CPhysicalQuantity(0, CTimeUnit::nullUnit())
         {
             CTime converted(time.hour(), time.minute(), time.second());
             (*this) = converted;
diff --git a/src/blackmisc/pq/time.h b/src/blackmisc/pq/time.h
index 0a853fdc6..058733a88 100644
--- a/src/blackmisc/pq/time.h
+++ b/src/blackmisc/pq/time.h
@@ -52,7 +52,7 @@ namespace BlackMisc
             CTime(int hours, int minutes, int seconds = 0);
 
             //! By Qt time
-            CTime(const QTime &time, bool negative = false);
+            CTime(QTime time, bool negative = false);
 
             //! \copydoc CPhysicalQuantity(const QString &unitString)
             CTime(const QString &unitString) : CPhysicalQuantity(0, CTimeUnit::nullUnit()) { this->parseFromString(unitString); }
diff --git a/src/blackmisc/simulation/aircraftmodel.cpp b/src/blackmisc/simulation/aircraftmodel.cpp
index f93411712..ed963c5d5 100644
--- a/src/blackmisc/simulation/aircraftmodel.cpp
+++ b/src/blackmisc/simulation/aircraftmodel.cpp
@@ -691,7 +691,7 @@ namespace BlackMisc
             return i; // default
         }
 
-        CAircraftModel CAircraftModel::fromDatabaseJson(const QJsonObject &json, const QString prefix)
+        CAircraftModel CAircraftModel::fromDatabaseJson(const QJsonObject &json, const QString &prefix)
         {
             const QString modelString(json.value(prefix + "modelstring").toString());
             const QString modelDescription(json.value(prefix + "description").toString());
diff --git a/src/blackmisc/simulation/aircraftmodel.h b/src/blackmisc/simulation/aircraftmodel.h
index 54f1e82c1..42ab7a10e 100644
--- a/src/blackmisc/simulation/aircraftmodel.h
+++ b/src/blackmisc/simulation/aircraftmodel.h
@@ -399,7 +399,7 @@ namespace BlackMisc
             static const QString &modelModeToString(ModelMode mode);
 
             //! From swift DB JSON
-            static CAircraftModel fromDatabaseJson(const QJsonObject &json, const QString prefix = QString("mod_"));
+            static CAircraftModel fromDatabaseJson(const QJsonObject &json, const QString &prefix = QString("mod_"));
 
             //! Split swift network string "DLH._STD [modelname]"
             //! \return QStringList [0] livery code , [1] model string
diff --git a/src/blackmisc/simulation/simulatorinfo.cpp b/src/blackmisc/simulation/simulatorinfo.cpp
index 2c665df73..bb4b9918a 100644
--- a/src/blackmisc/simulation/simulatorinfo.cpp
+++ b/src/blackmisc/simulation/simulatorinfo.cpp
@@ -282,7 +282,7 @@ namespace BlackMisc
             return sim;
         }
 
-        CSimulatorInfo CSimulatorInfo::fromDatabaseJson(const QJsonObject &json, const QString prefix)
+        CSimulatorInfo CSimulatorInfo::fromDatabaseJson(const QJsonObject &json, const QString &prefix)
         {
             const bool fsx = CDatastoreUtility::dbBoolStringToBool(json.value(prefix + "simfsx").toString());
             const bool fs9 = CDatastoreUtility::dbBoolStringToBool(json.value(prefix + "simfs9").toString());
diff --git a/src/blackmisc/simulation/simulatorinfo.h b/src/blackmisc/simulation/simulatorinfo.h
index 5d4e8322b..d2015f31c 100644
--- a/src/blackmisc/simulation/simulatorinfo.h
+++ b/src/blackmisc/simulation/simulatorinfo.h
@@ -178,7 +178,7 @@ namespace BlackMisc
             static const CSimulatorInfo &guessDefaultSimulator();
 
             //! From database JSON
-            static CSimulatorInfo fromDatabaseJson(const QJsonObject &json, const QString prefix);
+            static CSimulatorInfo fromDatabaseJson(const QJsonObject &json, const QString &prefix);
 
         private:
             int m_simulator = static_cast<int>(None);
diff --git a/src/blackmisc/simulation/simulatorinternals.cpp b/src/blackmisc/simulation/simulatorinternals.cpp
index f86c814cf..e6a674087 100644
--- a/src/blackmisc/simulation/simulatorinternals.cpp
+++ b/src/blackmisc/simulation/simulatorinternals.cpp
@@ -37,12 +37,12 @@ namespace BlackMisc
             return m_data.getNames(true);
         }
 
-        void CSimulatorInternals::setSimulatorVersion(const QString versionInfo)
+        void CSimulatorInternals::setSimulatorVersion(const QString &versionInfo)
         {
             this->setValue("all/versionInfo", versionInfo);
         }
 
-        void CSimulatorInternals::setSimulatorInstallationDirectory(const QString fullFilePath)
+        void CSimulatorInternals::setSimulatorInstallationDirectory(const QString &fullFilePath)
         {
             this->setValue("all/installDir", fullFilePath);
         }
diff --git a/src/blackmisc/simulation/simulatorinternals.h b/src/blackmisc/simulation/simulatorinternals.h
index 2f53987ed..6de06b27e 100644
--- a/src/blackmisc/simulation/simulatorinternals.h
+++ b/src/blackmisc/simulation/simulatorinternals.h
@@ -72,13 +72,13 @@ namespace BlackMisc
             QString getSimulatorVersion() const;
 
             //! Simulator version info, something like "10.3.2"
-            void setSimulatorVersion(const QString versionInfo);
+            void setSimulatorVersion(const QString &versionInfo);
 
             //! Path where simulator is installed
             QString getSimulatorInstallationDirectory() const;
 
             //! Path where simulator is installed
-            void setSimulatorInstallationDirectory(const QString fullFilePath);
+            void setSimulatorInstallationDirectory(const QString &fullFilePath);
 
             //! \copydoc BlackMisc::Mixin::Index::propertyByIndex
             CVariant propertyByIndex(const BlackMisc::CPropertyIndex &index) const;
diff --git a/src/blackmisc/statusmessage.h b/src/blackmisc/statusmessage.h
index 85a123cc5..1af7e99a9 100644
--- a/src/blackmisc/statusmessage.h
+++ b/src/blackmisc/statusmessage.h
@@ -68,22 +68,22 @@ namespace BlackMisc
         Derived &debug() { return setSeverityAndMessage(SeverityDebug, ""); }
 
         //! Set the severity to info, providing a format string.
-        Derived &info(QString format) { return setSeverityAndMessage(SeverityInfo, format); }
+        Derived &info(const QString &format) { return setSeverityAndMessage(SeverityInfo, format); }
 
         //! Set the severity to warning, providing a format string.
-        Derived &warning(QString format) { return setSeverityAndMessage(SeverityWarning, format); }
+        Derived &warning(const QString &format) { return setSeverityAndMessage(SeverityWarning, format); }
 
         //! Set the severity to error, providing a format string.
-        Derived &error(QString format) { return setSeverityAndMessage(SeverityError, format); }
+        Derived &error(const QString &format) { return setSeverityAndMessage(SeverityError, format); }
 
         //! Set the severity to info, providing a format string, and adding the validation category.
-        Derived &validationInfo(QString format) { setValidation(); return setSeverityAndMessage(SeverityInfo, format); }
+        Derived &validationInfo(const QString &format) { setValidation(); return setSeverityAndMessage(SeverityInfo, format); }
 
         //! Set the severity to warning, providing a format string, and adding the validation category.
-        Derived &validationWarning(QString format) { setValidation(); return setSeverityAndMessage(SeverityWarning, format); }
+        Derived &validationWarning(const QString &format) { setValidation(); return setSeverityAndMessage(SeverityWarning, format); }
 
         //! Set the severity to error, providing a format string, and adding the validation category.
-        Derived &validationError(QString format) { setValidation(); return setSeverityAndMessage(SeverityError, format); }
+        Derived &validationError(const QString &format) { setValidation(); return setSeverityAndMessage(SeverityError, format); }
 
         //! Streaming operators.
         //! \details If the format string is empty, the message will consist of all streamed values separated by spaces.
@@ -109,7 +109,7 @@ namespace BlackMisc
     private:
         void setValidation() { m_categories.remove(CLogCategory::uncategorized()); m_categories.push_back(CLogCategory::validation()); }
         Derived &setSeverityAndMessage(StatusSeverity s, const QString &m) { m_message = m; m_severity = s; return derived(); }
-        Derived &arg(QString value) { m_args.push_back(value); return derived(); }
+        Derived &arg(const QString &value) { m_args.push_back(value); return derived(); }
         Derived &derived() { return static_cast<Derived &>(*this); }
 
     protected:
diff --git a/src/blackmisc/test/testservice.cpp b/src/blackmisc/test/testservice.cpp
index c28933aa1..00b15b2a7 100644
--- a/src/blackmisc/test/testservice.cpp
+++ b/src/blackmisc/test/testservice.cpp
@@ -170,7 +170,7 @@ namespace BlackMisc
         void CTestService::receiveVariantList(const CVariantList &variantList) const
         {
             if (m_verbose) out() << "Pid: " << CTestService::getPid() << " " << variantList.size() << endl;
-            for (CVariant lv : variantList)
+            for (const CVariant &lv : variantList)
             {
                 if (m_verbose) out() << "    Received variant: " << lv.toQString() << endl;
             }
diff --git a/src/blackmisc/test/testserviceinterface.h b/src/blackmisc/test/testserviceinterface.h
index d86bf7042..5ab99b08e 100644
--- a/src/blackmisc/test/testserviceinterface.h
+++ b/src/blackmisc/test/testserviceinterface.h
@@ -188,21 +188,21 @@ namespace BlackMisc
                 return asyncCallWithArgumentList(QLatin1String("pingAircraftModelList"), argumentList);
             }
 
-            QDBusPendingReply<BlackMisc::Simulation::CSimulatedAircraft> pingSimulatedAircraft(BlackMisc::Simulation::CSimulatedAircraft aircraft)
+            QDBusPendingReply<BlackMisc::Simulation::CSimulatedAircraft> pingSimulatedAircraft(const BlackMisc::Simulation::CSimulatedAircraft &aircraft)
             {
                 QList<QVariant> argumentList;
                 argumentList << QVariant::fromValue(aircraft);
                 return asyncCallWithArgumentList(QLatin1String("pingSimulatedAircraft"), argumentList);
             }
 
-            QDBusPendingReply<BlackMisc::Simulation::CSimulatorPluginInfo> pingPluginInfo(BlackMisc::Simulation::CSimulatorPluginInfo info)
+            QDBusPendingReply<BlackMisc::Simulation::CSimulatorPluginInfo> pingPluginInfo(const BlackMisc::Simulation::CSimulatorPluginInfo &info)
             {
                 QList<QVariant> argumentList;
                 argumentList << QVariant::fromValue(info);
                 return asyncCallWithArgumentList(QLatin1String("pingPluginInfo"), argumentList);
             }
 
-            QDBusPendingReply<BlackMisc::Aviation::CAtcStationList> pingAtcStationList(BlackMisc::Aviation::CAtcStationList atcStationList)
+            QDBusPendingReply<BlackMisc::Aviation::CAtcStationList> pingAtcStationList(const BlackMisc::Aviation::CAtcStationList &atcStationList)
             {
                 QList<QVariant> argumentList;
                 argumentList << QVariant::fromValue(atcStationList);
@@ -258,7 +258,7 @@ namespace BlackMisc
                 return asyncCallWithArgumentList(QLatin1String("pingPropertyIndex"), argumentList);
             }
 
-            QDBusPendingReply<BlackMisc::CPropertyIndexVariantMap> pingIndexVariantMap(BlackMisc::CPropertyIndexVariantMap indexVariantMap)
+            QDBusPendingReply<BlackMisc::CPropertyIndexVariantMap> pingIndexVariantMap(const BlackMisc::CPropertyIndexVariantMap &indexVariantMap)
             {
                 QList<QVariant> argumentList;
                 argumentList << QVariant::fromValue(indexVariantMap);
@@ -342,7 +342,7 @@ namespace BlackMisc
                 return asyncCallWithArgumentList(QLatin1String("receiveStringMessage"), argumentList);
             }
 
-            QDBusPendingReply<> receiveTrack(BlackMisc::Aviation::CTrack track)
+            QDBusPendingReply<> receiveTrack(const BlackMisc::Aviation::CTrack &track)
             {
                 QList<QVariant> argumentList;
                 argumentList << QVariant::fromValue(track);
diff --git a/src/blackmisc/weather/cloudlayer.cpp b/src/blackmisc/weather/cloudlayer.cpp
index 634cdebbb..1ac5a7c26 100644
--- a/src/blackmisc/weather/cloudlayer.cpp
+++ b/src/blackmisc/weather/cloudlayer.cpp
@@ -20,16 +20,16 @@ namespace BlackMisc
     namespace Weather
     {
 
-        CCloudLayer::CCloudLayer(BlackMisc::Aviation::CAltitude base,
-                                 BlackMisc::Aviation::CAltitude top,
+        CCloudLayer::CCloudLayer(const BlackMisc::Aviation::CAltitude &base,
+                                 const BlackMisc::Aviation::CAltitude &top,
                                  Coverage coverage) :
             m_base(base), m_top(top)
         {
             setCoverage(coverage);
         }
 
-        CCloudLayer::CCloudLayer(BlackMisc::Aviation::CAltitude base,
-                                 BlackMisc::Aviation::CAltitude top,
+        CCloudLayer::CCloudLayer(const BlackMisc::Aviation::CAltitude &base,
+                                 const BlackMisc::Aviation::CAltitude &top,
                                  double precipitationRate,
                                  Precipitation precipitation,
                                  Clouds clouds,
diff --git a/src/blackmisc/weather/cloudlayer.h b/src/blackmisc/weather/cloudlayer.h
index 636125777..53df1ed54 100644
--- a/src/blackmisc/weather/cloudlayer.h
+++ b/src/blackmisc/weather/cloudlayer.h
@@ -78,13 +78,13 @@ namespace BlackMisc
             CCloudLayer() = default;
 
             //! Constructor
-            CCloudLayer(BlackMisc::Aviation::CAltitude base,
-                        BlackMisc::Aviation::CAltitude top,
+            CCloudLayer(const BlackMisc::Aviation::CAltitude &base,
+                        const BlackMisc::Aviation::CAltitude &top,
                         Coverage coverage);
 
             //! Constructor
-            CCloudLayer(BlackMisc::Aviation::CAltitude base,
-                        BlackMisc::Aviation::CAltitude top,
+            CCloudLayer(const BlackMisc::Aviation::CAltitude &base,
+                        const BlackMisc::Aviation::CAltitude &top,
                         double precipitationRate,
                         Precipitation precipitation,
                         Clouds clouds,
@@ -97,7 +97,7 @@ namespace BlackMisc
             BlackMisc::Aviation::CAltitude getBase() const { return m_base; }
 
             //! Set layer top
-            void setTop(BlackMisc::Aviation::CAltitude top) { m_top = top; }
+            void setTop(const BlackMisc::Aviation::CAltitude &top) { m_top = top; }
 
             //! Get layer top
             BlackMisc::Aviation::CAltitude getTop() const { return m_top; }
diff --git a/src/blackmisc/windllutils.cpp b/src/blackmisc/windllutils.cpp
index 2e4da8800..67b10d500 100644
--- a/src/blackmisc/windllutils.cpp
+++ b/src/blackmisc/windllutils.cpp
@@ -29,7 +29,7 @@ namespace BlackMisc
             WORD wCodePage;
         };
 
-        QString languageToIsoCode(const LanguageCodePage &codePage)
+        QString languageToIsoCode(LanguageCodePage codePage)
         {
             const LCID locale = codePage.wLanguage;
             const int nchars = GetLocaleInfo(locale, LOCALE_SISO639LANGNAME, NULL, 0);
@@ -39,7 +39,7 @@ namespace BlackMisc
             return iso;
         }
 
-        QString queryStringFileInfo(BYTE *pbVersionInfo, const LanguageCodePage &codePage, const QString &stringName)
+        QString queryStringFileInfo(BYTE *pbVersionInfo, LanguageCodePage codePage, const QString &stringName)
         {
             constexpr int fieldWidth = 4;
             constexpr int base = 16;
diff --git a/src/blacksound/soundgenerator.cpp b/src/blacksound/soundgenerator.cpp
index e2a668418..ff66a3632 100644
--- a/src/blacksound/soundgenerator.cpp
+++ b/src/blacksound/soundgenerator.cpp
@@ -401,7 +401,7 @@ namespace BlackSound
         QAudioDeviceInfo qtDevice = QAudioDeviceInfo::defaultOutputDevice();
         if (lookFor.startsWith("default")) { return qtDevice; }
         int score = 0;
-        foreach(QAudioDeviceInfo qd, QAudioDeviceInfo::availableDevices(QAudio::AudioOutput))
+        for (const QAudioDeviceInfo &qd : QAudioDeviceInfo::availableDevices(QAudio::AudioOutput))
         {
             const QString cn = qd.deviceName().toLower();
             if (lookFor == cn) { return qd;  } // exact match
@@ -425,7 +425,7 @@ namespace BlackSound
         return qtDevice;
     }
 
-    CSoundGenerator *CSoundGenerator::playSignal(int volume, const QList<CSoundGenerator::Tone> &tones, QAudioDeviceInfo device)
+    CSoundGenerator *CSoundGenerator::playSignal(int volume, const QList<CSoundGenerator::Tone> &tones, const QAudioDeviceInfo &device)
     {
         CSoundGenerator *generator = new CSoundGenerator(device, CSoundGenerator::defaultAudioFormat(), tones, CNotificationSounds::SingleWithAutomaticDeletion);
         if (tones.isEmpty()) { return generator; } // that was easy
@@ -437,7 +437,7 @@ namespace BlackSound
         return generator;
     }
 
-    CSoundGenerator *CSoundGenerator::playSignalInBackground(int volume, const QList<CSoundGenerator::Tone> &tones, QAudioDeviceInfo device)
+    CSoundGenerator *CSoundGenerator::playSignalInBackground(int volume, const QList<CSoundGenerator::Tone> &tones, const QAudioDeviceInfo &device)
     {
         CSoundGenerator *generator = new CSoundGenerator(device, CSoundGenerator::defaultAudioFormat(), tones, CNotificationSounds::SingleWithAutomaticDeletion);
         if (tones.isEmpty()) { return generator; } // that was easy
@@ -449,7 +449,7 @@ namespace BlackSound
         return generator;
     }
 
-    void CSoundGenerator::playSignalRecorded(int volume, const QList<CSoundGenerator::Tone> &tones, QAudioDeviceInfo device)
+    void CSoundGenerator::playSignalRecorded(int volume, const QList<CSoundGenerator::Tone> &tones, const QAudioDeviceInfo &device)
     {
         if (tones.isEmpty()) { return; } // that was easy
         if (volume < 1) { return; }
@@ -467,7 +467,7 @@ namespace BlackSound
         generator->deleteLater();
     }
 
-    void CSoundGenerator::playSelcal(int volume, const BlackMisc::Aviation::CSelcal &selcal, QAudioDeviceInfo device)
+    void CSoundGenerator::playSelcal(int volume, const BlackMisc::Aviation::CSelcal &selcal, const QAudioDeviceInfo &device)
     {
         QList<CSoundGenerator::Tone> tones;
         if (selcal.isValid())
@@ -535,13 +535,13 @@ namespace BlackSound
     void CSoundGenerator::printAllQtSoundDevices(QTextStream &out)
     {
         out << "output:" << endl;
-        foreach(QAudioDeviceInfo qd, QAudioDeviceInfo::availableDevices(QAudio::AudioOutput))
+        for (const QAudioDeviceInfo &qd : QAudioDeviceInfo::availableDevices(QAudio::AudioOutput))
         {
             out << qd.deviceName() << endl;
         }
 
         out << "input:" << endl;
-        foreach(QAudioDeviceInfo qd, QAudioDeviceInfo::availableDevices(QAudio::AudioInput))
+        for (const QAudioDeviceInfo &qd : QAudioDeviceInfo::availableDevices(QAudio::AudioInput))
         {
             out << qd.deviceName() << endl;
         }
diff --git a/src/blacksound/soundgenerator.h b/src/blacksound/soundgenerator.h
index 77470bad4..91d0e1d93 100644
--- a/src/blacksound/soundgenerator.h
+++ b/src/blacksound/soundgenerator.h
@@ -125,27 +125,27 @@ namespace BlackSound
         //! \param tones     list of tones
         //! \param device    device to be used
         //! \return generator used, important with SingleWithAutomaticDeletion automatically deleted
-        static CSoundGenerator *playSignal(int volume, const QList<Tone> &tones, QAudioDeviceInfo device = QAudioDeviceInfo::defaultOutputDevice());
+        static CSoundGenerator *playSignal(int volume, const QList<Tone> &tones, const QAudioDeviceInfo &device = QAudioDeviceInfo::defaultOutputDevice());
 
         //! Play signal of tones once
         //! \param volume    0-100
         //! \param tones     list of tones
         //! \param device    device to be used
         //! \return generator used, important with SingleWithAutomaticDeletion automatically deleted
-        static CSoundGenerator *playSignalInBackground(int volume, const QList<CSoundGenerator::Tone> &tones, QAudioDeviceInfo device);
+        static CSoundGenerator *playSignalInBackground(int volume, const QList<CSoundGenerator::Tone> &tones, const QAudioDeviceInfo &device);
 
         //! Record the tones to a wav file, then play the wav file
         //! \param volume    0-100
         //! \param tones     list of tones
         //! \param device    device to be used
-        static void playSignalRecorded(int volume, const QList<CSoundGenerator::Tone> &tones, QAudioDeviceInfo device);
+        static void playSignalRecorded(int volume, const QList<CSoundGenerator::Tone> &tones, const QAudioDeviceInfo &device);
 
         //! Play SELCAL tone
         //! \param volume    0-100
         //! \param selcal
         //! \param device    device to be used
         //! \see BlackMisc::Aviation::CSelcal
-        static void playSelcal(int volume, const BlackMisc::Aviation::CSelcal &selcal, QAudioDeviceInfo device = QAudioDeviceInfo::defaultOutputDevice());
+        static void playSelcal(int volume, const BlackMisc::Aviation::CSelcal &selcal, const QAudioDeviceInfo &device = QAudioDeviceInfo::defaultOutputDevice());
 
         //! Play SELCAL tone
         //! \param volume    0-100
diff --git a/src/plugins/simulator/xplane/simulatorxplane.cpp b/src/plugins/simulator/xplane/simulatorxplane.cpp
index 57ece0b3b..266cb5b61 100644
--- a/src/plugins/simulator/xplane/simulatorxplane.cpp
+++ b/src/plugins/simulator/xplane/simulatorxplane.cpp
@@ -466,7 +466,7 @@ namespace BlackSimPlugin
                 if (package.isEmpty()) { continue; }
                 packages.insert(it, { package.append('/') });
             }
-            for (auto package : packages)
+            for (auto &package : packages)
             {
                 Q_ASSERT(package.s.endsWith('/'));
                 package.s.chop(1);
diff --git a/src/xbus/menus.cpp b/src/xbus/menus.cpp
index 25f16cf92..3726a92f0 100644
--- a/src/xbus/menus.cpp
+++ b/src/xbus/menus.cpp
@@ -49,7 +49,7 @@ namespace XBus
         return { XPLMFindPluginsMenu(), true, nullptr };
     }
 
-    CMenuItem CMenu::item(std::string name, std::function<void()> callback)
+    CMenuItem CMenu::item(const std::string &name, std::function<void()> callback)
     {
         assert(! name.empty());
         m_data->items->emplace_back(
@@ -59,7 +59,7 @@ namespace XBus
         return m_data->items->back().first;
     }
 
-    CMenuItem CMenu::checkableItem(std::string name, bool checked, std::function<void(bool)> callback)
+    CMenuItem CMenu::checkableItem(const std::string &name, bool checked, std::function<void(bool)> callback)
     {
         assert(! name.empty());
         m_data->items->emplace_back(
@@ -74,7 +74,7 @@ namespace XBus
         XPLMAppendMenuSeparator(m_data->id);
     }
 
-    CMenu CMenu::subMenu(std::string name)
+    CMenu CMenu::subMenu(const std::string &name)
     {
         assert(! name.empty());
         auto items = std::make_unique<ItemList>();
diff --git a/src/xbus/menus.h b/src/xbus/menus.h
index 3e358ba88..7d235d924 100644
--- a/src/xbus/menus.h
+++ b/src/xbus/menus.h
@@ -68,16 +68,16 @@ namespace XBus
         static CMenu mainMenu();
 
         //! Appends an item to the menu and returns it.
-        CMenuItem item(std::string name, std::function<void()> callback);
+        CMenuItem item(const std::string &name, std::function<void()> callback);
 
         //! Appends a checkbox item to the menu and returns it.
-        CMenuItem checkableItem(std::string name, bool checked, std::function<void(bool)> callback);
+        CMenuItem checkableItem(const std::string &name, bool checked, std::function<void(bool)> callback);
 
         //! Appends a separator to the menu.
         void sep();
 
         //! Appends an item to the menu which opens a sub-menu, and returns it.
-        CMenu subMenu(std::string name);
+        CMenu subMenu(const std::string &name);
 
     private:
         typedef std::vector<std::pair<CMenuItem, std::function<void(bool)>>> ItemList;
diff --git a/tests/blackcore/testnetwork.cpp b/tests/blackcore/testnetwork.cpp
index 8341fbde6..e347fa0cd 100644
--- a/tests/blackcore/testnetwork.cpp
+++ b/tests/blackcore/testnetwork.cpp
@@ -76,7 +76,7 @@ namespace BlackCoreTest
 
         EXPECT_UNIT(e)
         .send(&INetwork::sendPing, "server")
-        .expect(&INetwork::pongReceived, [](CCallsign callsign, PhysicalQuantities::CTime elapsedTime)
+        .expect(&INetwork::pongReceived, [](const CCallsign &callsign, const PhysicalQuantities::CTime &elapsedTime)
         {
             qDebug() << "PONG" << callsign << elapsedTime;
         })