Thank you kindly, RemedyTomm, for a patch that fixes:

llSetPrimitiveParams in a large linkset can disrupt the 
entire region. However, when the script is in a large 
linkset, it appears to totally lag out the scene and 
stops updates from being sent.

OpenSim/Region/Framework/Scenes/SceneObjectPart.cs

@@ -3557,7 +3557,10 @@ if (m_shape != null) {
             TriggerScriptChangedEvent(Changed.TEXTURE);
 
             ParentGroup.HasGroupChanged = true;
-            ParentGroup.ScheduleGroupForFullUpdate();
+            //This is madness..
+            //ParentGroup.ScheduleGroupForFullUpdate();
+            //This is sparta
+            ScheduleFullUpdate();
         }
 
         public void aggregateScriptEvents()