Index: /OpenSceneGraph/trunk/include/osgUtil/GLObjectsVisitor
===================================================================
--- /OpenSceneGraph/trunk/include/osgUtil/GLObjectsVisitor (revision 9377)
+++ /OpenSceneGraph/trunk/include/osgUtil/GLObjectsVisitor (revision 9868)
@@ -124,5 +124,5 @@
 
         virtual void operator () (osg::GraphicsContext* context);
-
+        
     protected:
     
@@ -131,4 +131,108 @@
 };
 
+class OSGUTIL_EXPORT IncrementalCompileOperation : public osg::GraphicsOperation
+{
+    public:
+
+        IncrementalCompileOperation();
+        
+        typedef std::vector<osg::GraphicsContext*> Contexts;
+        void assignContexts(Contexts& contexts);
+        void removeContexts(Contexts& contexts);
+
+        void addGraphicsContext(osg::GraphicsContext* gc);
+        void removeGraphicsContext(osg::GraphicsContext* gc);
+
+
+        /** Merge subgraphs that have been compiled.*/
+        void mergeCompiledSubgraphs();
+
+        virtual void operator () (osg::GraphicsContext* context);
+        
+
+
+        struct CompileData : public osg::Referenced
+        {
+            typedef std::list< osg::ref_ptr<osg::Texture> >  Textures;
+            typedef std::list< osg::ref_ptr<osg::Drawable> > Drawables;
+            typedef std::list< osg::ref_ptr<osg::Program> >  Programs;
+            
+            bool empty() const { return _textures.empty() && _drawables.empty() && _programs.empty(); }
+            
+            Textures    _textures;
+            Drawables   _drawables;
+            Programs    _programs;
+        };
+
+        class CompileSet;
+        typedef std::set<osg::GraphicsContext*> ContextSet;
+        typedef std::map<osg::GraphicsContext*, osg::ref_ptr<CompileData> >  CompileMap;
+        
+        struct CompileCompletedCallback : public osg::Referenced
+        {
+            virtual bool compileCompleted(CompileSet* compileSet) = 0;
+        };
+
+        class CompileSet : public osg::Referenced
+        {
+        public:
+        
+            
+            CompileSet() {}
+            
+            CompileSet(osg::Node*subgraphToCompile):
+                _subgraphToCompile(subgraphToCompile) {}
+
+            CompileSet(osg::Group* attachmentPoint, osg::Node*subgraphToCompile):
+                _attachmentPoint(attachmentPoint),
+                _subgraphToCompile(subgraphToCompile) {}
+        
+            void buildCompileMap(ContextSet& context);
+
+            osg::ref_ptr<osg::Group>                _attachmentPoint;
+            osg::ref_ptr<osg::Node>                 _subgraphToCompile;
+            osg::ref_ptr<CompileCompletedCallback>  _compileCompletedCallback;
+            CompileMap                              _compileMap;
+            
+        // protected:
+        
+            virtual ~CompileSet() {}
+        };
+        
+        typedef std::list< osg::ref_ptr<CompileSet> >  CompileSets;
+
+
+        /** Add a subgraph to be compiled.*/
+        void add(osg::Node* subgraphToCompile);
+
+        /** Add a subgraph to be compiled and add automatically to attachPoint on call to mergeCompiledSubgraphs.*/
+        void add(osg::Group* attachmentPoint, osg::Node* subgraphToCompile);
+
+        /** Add a CompileSet to be compiled.*/
+        void add(CompileSet* compileSet, bool callBuildCompileMap=true);
+
+
+        OpenThreads::Mutex& getToCompiledMutex() { return _toCompileMutex; }
+        CompileSets& getToCompile() { return _compiled; }
+        
+        OpenThreads::Mutex& getCompiledMutex() { return _compiledMutex; }
+        CompileSets& getCompiled() { return _compiled; }
+
+    protected:
+
+        virtual ~IncrementalCompileOperation();
+
+    
+        OpenThreads::Mutex  _toCompileMutex;
+        CompileSets         _toCompile;
+        
+        OpenThreads::Mutex  _compiledMutex;
+        CompileSets         _compiled;
+        
+        ContextSet          _contexts;
+
+};
+
+
 }
 
Index: /OpenSceneGraph/trunk/include/osgViewer/ViewerBase
===================================================================
--- /OpenSceneGraph/trunk/include/osgViewer/ViewerBase (revision 9554)
+++ /OpenSceneGraph/trunk/include/osgViewer/ViewerBase (revision 9868)
@@ -18,4 +18,5 @@
 
 #include <osgUtil/UpdateVisitor>
+#include <osgUtil/GLObjectsVisitor>
 
 #include <osgGA/MatrixManipulator>
@@ -185,4 +186,13 @@
         /** Get the graphics operation to call on realization of the viewers graphics windows.*/
         osg::Operation* getRealizeOperation() { return _realizeOperation.get(); }
+        
+        
+        /** Set the incremental compile operation.
+          * Used to manage the OpenGL object compilation and merging of subgraphs in a way that avoids overloading
+          * the rendering of frame with too many new objects in one frame. */
+        void setIncrementalCompileOperation(osgUtil::IncrementalCompileOperation* ico);
+
+        /** Get the incremental compile operation. */
+        osgUtil::IncrementalCompileOperation* getIncrementalCompileOperation() { return _incrementalCompileOperation.get(); }
 
 
@@ -261,27 +271,28 @@
         virtual void viewerInit() = 0;
 
-        bool                                        _firstFrame;
-        bool                                        _done;
-        int                                         _keyEventSetsDone;
-        bool                                        _quitEventSetsDone;
-        bool                                        _releaseContextAtEndOfFrameHint;
-        
-        ThreadingModel                              _threadingModel;
-        bool                                        _threadsRunning;
-
-        BarrierPosition                             _endBarrierPosition;
-
-        osg::ref_ptr<osg::BarrierOperation>         _startRenderingBarrier;
-        osg::ref_ptr<osg::BarrierOperation>         _endRenderingDispatchBarrier;
-        osg::ref_ptr<osg::EndOfDynamicDrawBlock>    _endDynamicDrawBlock;
-        
-        osg::ref_ptr<osgGA::EventVisitor>           _eventVisitor;
-        
-        osg::ref_ptr<osg::OperationQueue>           _updateOperations;
-        osg::ref_ptr<osgUtil::UpdateVisitor>        _updateVisitor;
-        
-        osg::ref_ptr<osg::Operation>                _realizeOperation;
-
-        osg::observer_ptr<osg::GraphicsContext>     _currentContext;
+        bool                                                _firstFrame;
+        bool                                                _done;
+        int                                                 _keyEventSetsDone;
+        bool                                                _quitEventSetsDone;
+        bool                                                _releaseContextAtEndOfFrameHint;
+        
+        ThreadingModel                                      _threadingModel;
+        bool                                                _threadsRunning;
+
+        BarrierPosition                                     _endBarrierPosition;
+
+        osg::ref_ptr<osg::BarrierOperation>                 _startRenderingBarrier;
+        osg::ref_ptr<osg::BarrierOperation>                 _endRenderingDispatchBarrier;
+        osg::ref_ptr<osg::EndOfDynamicDrawBlock>            _endDynamicDrawBlock;
+        
+        osg::ref_ptr<osgGA::EventVisitor>                   _eventVisitor;
+        
+        osg::ref_ptr<osg::OperationQueue>                   _updateOperations;
+        osg::ref_ptr<osgUtil::UpdateVisitor>                _updateVisitor;
+        
+        osg::ref_ptr<osg::Operation>                        _realizeOperation;
+        osg::ref_ptr<osgUtil::IncrementalCompileOperation>  _incrementalCompileOperation;
+
+        osg::observer_ptr<osg::GraphicsContext>             _currentContext;
 };
 
Index: /OpenSceneGraph/trunk/src/osgUtil/GLObjectsVisitor.cpp
===================================================================
--- /OpenSceneGraph/trunk/src/osgUtil/GLObjectsVisitor.cpp (revision 8360)
+++ /OpenSceneGraph/trunk/src/osgUtil/GLObjectsVisitor.cpp (revision 9868)
@@ -14,8 +14,14 @@
 #include <osg/Drawable>
 #include <osg/Notify>
+#include <OpenThreads/ScopedLock>
 
 using namespace osg;
 using namespace osgUtil;
 
+
+/////////////////////////////////////////////////////////////////
+//
+// GLObjectsVisitor
+//
 GLObjectsVisitor::GLObjectsVisitor(Mode mode)
 {
@@ -146,4 +152,9 @@
 }
 
+/////////////////////////////////////////////////////////////////
+//
+// GLObjectsVisitor
+//
+
 GLObjectsOperation::GLObjectsOperation(GLObjectsVisitor::Mode mode):
     osg::GraphicsOperation("GLObjectOperation",false),
@@ -183,2 +194,155 @@
     // osg::notify(osg::NOTICE)<<"GLObjectsOperation::after >>>>>>>>>>> "<<std::endl;
 }
+
+/////////////////////////////////////////////////////////////////
+//
+// IncrementalCompileOperation
+//
+IncrementalCompileOperation::IncrementalCompileOperation():
+    osg::GraphicsOperation("IncrementalCompileOperation",true)
+{
+}
+
+IncrementalCompileOperation::~IncrementalCompileOperation()
+{
+}
+
+void IncrementalCompileOperation::assignContexts(Contexts& contexts)
+{
+    for(Contexts::iterator itr = contexts.begin();
+        itr != contexts.end();
+        ++itr)
+    {
+        osg::GraphicsContext* gc = *itr;
+        addGraphicsContext(gc);
+    }
+}
+
+void IncrementalCompileOperation::removeContexts(Contexts& contexts)
+{
+    for(Contexts::iterator itr = contexts.begin();
+        itr != contexts.end();
+        ++itr)
+    {
+        osg::GraphicsContext* gc = *itr;
+        removeGraphicsContext(gc);
+    }
+}
+
+
+void IncrementalCompileOperation::addGraphicsContext(osg::GraphicsContext* gc)
+{
+    if (_contexts.count(gc)==0)
+    {
+        gc->add(this);
+        _contexts.insert(gc);
+    }
+}
+
+void IncrementalCompileOperation::removeGraphicsContext(osg::GraphicsContext* gc)
+{
+    if (_contexts.count(gc)!=0)
+    {
+        gc->remove(this);
+        _contexts.erase(gc);
+    }
+}
+
+void IncrementalCompileOperation::add(osg::Node* subgraphToCompile)
+{
+    osg::notify(osg::NOTICE)<<"IncrementalCompileOperation::add("<<subgraphToCompile<<")"<<std::endl;
+    add(new CompileSet(subgraphToCompile));
+}
+
+void IncrementalCompileOperation::add(osg::Group* attachmentPoint, osg::Node* subgraphToCompile)
+{
+    osg::notify(osg::NOTICE)<<"IncrementalCompileOperation::add("<<attachmentPoint<<", "<<subgraphToCompile<<")"<<std::endl;
+    add(new CompileSet(attachmentPoint, subgraphToCompile));
+}
+
+
+void IncrementalCompileOperation::add(CompileSet* compileSet, bool callBuildCompileMap)
+{
+    if (!compileSet) return;
+    
+    if (callBuildCompileMap) compileSet->buildCompileMap(_contexts);
+
+    osg::notify(osg::NOTICE)<<"IncrementalCompileOperation::add(CompileSet = "<<compileSet<<", "<<", "<<callBuildCompileMap<<")"<<std::endl;
+
+    OpenThreads::ScopedLock<OpenThreads::Mutex>  lock(_toCompileMutex);
+    _toCompile.push_back(compileSet);
+}
+
+void IncrementalCompileOperation::mergeCompiledSubgraphs()
+{
+    osg::notify(osg::NOTICE)<<"IncrementalCompileOperation::mergeCompiledSubgraphs()"<<std::endl;
+
+    OpenThreads::ScopedLock<OpenThreads::Mutex>  compilded_lock(_compiledMutex);
+    
+    for(CompileSets::iterator itr = _compiled.begin(); 
+        itr != _compiled.end();
+        ++itr)
+    {
+        CompileSet* cs = itr->get();
+        if (cs->_attachmentPoint.valid())
+        {
+            cs->_attachmentPoint->addChild(cs->_subgraphToCompile.get());
+        }
+    }
+    
+    _compiled.clear();
+}
+
+void IncrementalCompileOperation::CompileSet::buildCompileMap(ContextSet& context)
+{
+}
+
+void IncrementalCompileOperation::operator () (osg::GraphicsContext* context)
+{
+    osg::notify(osg::NOTICE)<<"IncrementalCompileOperation::operator () ("<<context<<")"<<std::endl;
+
+    OpenThreads::ScopedLock<OpenThreads::Mutex>  toCompile_lock(_toCompileMutex);
+    for(CompileSets::iterator itr = _toCompile.begin(); 
+        itr != _toCompile.end();
+        )
+    {
+        CompileSet* cs = itr->get();
+        CompileMap& cm = cs->_compileMap;
+        CompileData* cd = cm[context].get();
+        
+        if (cd)
+        {        
+            // compile textures
+            cd->_textures.clear();
+
+            // compile drawables
+            cd->_drawables.clear();
+
+            // compile programs
+            cd->_programs.clear();
+        }
+                
+        if (!cd || cd->empty())
+        {
+            if (cs->_compileCompletedCallback.valid())
+            {
+                if (cs->_compileCompletedCallback->compileCompleted(cs))
+                {
+                    // callback will handle merging of subgraph so no need to place CompileSet in merge.
+                }
+                else
+                {
+                    OpenThreads::ScopedLock<OpenThreads::Mutex>  compilded_lock(_compiledMutex);
+                    _compiled.push_back(cs);
+                }
+            }
+        
+            // remove from toCompileSet;
+            itr = _toCompile.erase(itr);
+        }
+        else
+        {
+            ++itr;
+        }
+    }
+}
Index: /OpenSceneGraph/trunk/src/osg/GraphicsContext.cpp
===================================================================
--- /OpenSceneGraph/trunk/src/osg/GraphicsContext.cpp (revision 8872)
+++ /OpenSceneGraph/trunk/src/osg/GraphicsContext.cpp (revision 9868)
@@ -318,5 +318,5 @@
 GraphicsContext* GraphicsContext::getOrCreateCompileContext(unsigned int contextID)
 {
-    osg::notify(osg::INFO)<<"GraphicsContext::createCompileContext."<<std::endl;
+    osg::notify(osg::NOTICE)<<"GraphicsContext::createCompileContext."<<std::endl;
 
     {    
@@ -350,5 +350,5 @@
         OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_contextIDMapMutex);
         s_contextIDMap[contextID]._compileContext = gc;
-        osg::notify(osg::INFO)<<"   succeeded GraphicsContext::createCompileContext."<<std::endl;
+        osg::notify(osg::NOTICE)<<"   succeeded GraphicsContext::createCompileContext."<<std::endl;
         return gc.release();
     }
Index: /OpenSceneGraph/trunk/src/osgViewer/Viewer.cpp
===================================================================
--- /OpenSceneGraph/trunk/src/osgViewer/Viewer.cpp (revision 9554)
+++ /OpenSceneGraph/trunk/src/osgViewer/Viewer.cpp (revision 9868)
@@ -449,5 +449,8 @@
         }
     }
-    
+
+    // attach contexts to _incrementalCompileOperation if attached.
+    if (_incrementalCompileOperation) _incrementalCompileOperation->assignContexts(contexts);
+
     bool grabFocus = true;
     if (grabFocus)
@@ -899,4 +902,11 @@
         _updateOperations->runOperations(this);
     }
+    
+    if (_incrementalCompileOperation.valid())
+    {
+        // merge subgraphs that have been compiled by the incremental compiler operation.
+        _incrementalCompileOperation->mergeCompiledSubgraphs();
+    }
+
 
     {
Index: /OpenSceneGraph/trunk/src/osgViewer/CompositeViewer.cpp
===================================================================
--- /OpenSceneGraph/trunk/src/osgViewer/CompositeViewer.cpp (revision 9554)
+++ /OpenSceneGraph/trunk/src/osgViewer/CompositeViewer.cpp (revision 9868)
@@ -498,4 +498,8 @@
     }
     
+    // attach contexts to _incrementalCompileOperation if attached.
+    if (_incrementalCompileOperation) _incrementalCompileOperation->assignContexts(contexts);
+
+
     bool grabFocus = true;
     if (grabFocus)
@@ -995,4 +999,10 @@
     }
 
+    if (_incrementalCompileOperation.valid())
+    {
+        // merge subgraphs that have been compiled by the incremental compiler operation.
+        _incrementalCompileOperation->mergeCompiledSubgraphs();
+    }
+
     if (_updateOperations.valid())
     {
Index: /OpenSceneGraph/trunk/src/osgViewer/ViewerBase.cpp
===================================================================
--- /OpenSceneGraph/trunk/src/osgViewer/ViewerBase.cpp (revision 9591)
+++ /OpenSceneGraph/trunk/src/osgViewer/ViewerBase.cpp (revision 9868)
@@ -376,5 +376,5 @@
         if (!gc->isRealized())
         {
-            osg::notify(osg::INFO)<<"ViewerBase::startThreading() : Realizng window "<<gc<<std::endl;
+            osg::notify(osg::INFO)<<"ViewerBase::startThreading() : Realizing window "<<gc<<std::endl;
             gc->realize();
         }
@@ -550,4 +550,19 @@
         _updateOperations->remove(operation);
     } 
+}
+
+void ViewerBase::setIncrementalCompileOperation(osgUtil::IncrementalCompileOperation* ico)
+{
+    if (_incrementalCompileOperation == ico) return;
+    
+    Contexts contexts;
+    getContexts(contexts, false);
+    
+    if (_incrementalCompileOperation.valid()) _incrementalCompileOperation->removeContexts(contexts);
+
+    // assign new operation        
+    _incrementalCompileOperation = ico;
+
+    if (_incrementalCompileOperation) _incrementalCompileOperation->assignContexts(contexts);
 }
 
Index: /OpenSceneGraph/trunk/examples/osgterrain/osgterrain.cpp
===================================================================
--- /OpenSceneGraph/trunk/examples/osgterrain/osgterrain.cpp (revision 9618)
+++ /OpenSceneGraph/trunk/examples/osgterrain/osgterrain.cpp (revision 9868)
@@ -58,4 +58,23 @@
 typedef std::vector< osg::ref_ptr<osg::GraphicsThread> > GraphicsThreads;
 
+struct ReleaseBlockOnCompileCompleted : public osgUtil::IncrementalCompileOperation::CompileCompletedCallback
+{
+
+    ReleaseBlockOnCompileCompleted(osg::RefBlockCount* block):
+        _block(block) {}
+
+    virtual bool compileCompleted(osgUtil::IncrementalCompileOperation::CompileSet* compileSet)
+    {
+        if (_block.valid()) _block->completed();
+        
+        // tell IncrementalCompileOperation that it's now safe to remove the compileSet
+        
+        osg::notify(osg::NOTICE)<<"compileCompleted("<<compileSet<<")"<<std::endl;
+        
+        return true;
+    }
+
+    osg::ref_ptr<osg::RefBlockCount> _block;
+};
 
 
@@ -64,8 +83,8 @@
 public:
 
-    LoadAndCompileOperation(const std::string& filename, GraphicsThreads& graphicsThreads, osg::RefBlockCount* block):
+    LoadAndCompileOperation(const std::string& filename, osgUtil::IncrementalCompileOperation* ico , osg::RefBlockCount* block):
         Operation("Load and compile Operation", false),
         _filename(filename),
-        _graphicsThreads(graphicsThreads),
+        _incrementalCompileOperation(ico),
         _block(block) {}
 
@@ -75,26 +94,26 @@
 
         _loadedModel = osgDB::readNodeFile(_filename);
-        if (_loadedModel.valid() && !_graphicsThreads.empty())
-        {
-            osg::ref_ptr<osgUtil::GLObjectsOperation> compileOperation = new osgUtil::GLObjectsOperation(_loadedModel.get());
-
-            for(GraphicsThreads::iterator gitr = _graphicsThreads.begin();
-                gitr != _graphicsThreads.end();
-                ++gitr)
-            {
-                (*gitr)->add( compileOperation.get() );
-                // requiresBarrier = true;
-            }
-        }
-        
-        if (_block.valid()) _block->completed();
+        
+        if (_loadedModel.valid() && _incrementalCompileOperation.valid())
+        {
+            osg::ref_ptr<osgUtil::IncrementalCompileOperation::CompileSet> compileSet = 
+                new osgUtil::IncrementalCompileOperation::CompileSet(_loadedModel);
+            
+            compileSet->_compileCompletedCallback = new ReleaseBlockOnCompileCompleted(_block.get());
+        
+            _incrementalCompileOperation->add(compileSet.get());
+        }
+        else 
+        {
+            if (_block.valid()) _block->completed();
+        }
 
         // osg::notify(osg::NOTICE)<<"done LoadAndCompileOperation "<<_filename<<std::endl;
     }
     
-    std::string                 _filename;
-    GraphicsThreads             _graphicsThreads;
-    osg::ref_ptr<osg::Node>     _loadedModel;
-    osg::ref_ptr<osg::RefBlockCount> _block;
+    std::string                                         _filename;
+    osg::ref_ptr<osg::Node>                             _loadedModel;
+    osg::ref_ptr<osgUtil::IncrementalCompileOperation>  _incrementalCompileOperation;
+    osg::ref_ptr<osg::RefBlockCount>                    _block;
 
 };
@@ -109,7 +128,8 @@
 
 
-    MasterOperation(const std::string& filename):
+    MasterOperation(const std::string& filename, osgUtil::IncrementalCompileOperation* ico):
         Operation("Master reading operation",true),
-        _filename(filename)
+        _filename(filename),
+        _incrementalCompileOperation(ico)
     {
     }
@@ -256,7 +276,4 @@
                 if (gt) threads.push_back(gt);
             }
-
-            bool requiresBarrier = false;
-
 
             if (_operationQueue.valid())
@@ -277,5 +294,5 @@
                     // osg::notify(osg::NOTICE)<<"Adding LoadAndCompileOperation "<<*nitr<<std::endl;
 
-                    osg::ref_ptr<LoadAndCompileOperation> loadAndCompile = new LoadAndCompileOperation( *nitr, threads, _endOfLoadBlock.get() );
+                    osg::ref_ptr<LoadAndCompileOperation> loadAndCompile = new LoadAndCompileOperation( *nitr, _incrementalCompileOperation.get(), _endOfLoadBlock.get() );
                     loadAndCompileList.push_back(loadAndCompile);
                     _operationQueue->add( loadAndCompile.get() );
@@ -301,5 +318,4 @@
                     {
                         nodesToAdd[(*litr)->_filename] = (*litr)->_loadedModel;
-                        requiresBarrier = true;
                     }
                 }
@@ -309,4 +325,9 @@
             else
             {
+
+                _endOfLoadBlock = new osg::RefBlockCount(newFiles.size());
+                
+                _endOfLoadBlock->reset();
+
                 for(Files::iterator nitr = newFiles.begin();
                     nitr != newFiles.end();
@@ -319,36 +340,28 @@
                         nodesToAdd[*nitr] = loadedModel;
 
-                        osg::ref_ptr<osgUtil::GLObjectsOperation> compileOperation = new osgUtil::GLObjectsOperation(loadedModel.get());
-
-                        for(GraphicsThreads::iterator gitr = threads.begin();
-                            gitr != threads.end();
-                            ++gitr)
+                        if (_incrementalCompileOperation.valid())
                         {
-                            (*gitr)->add( compileOperation.get() );
-                            requiresBarrier = true;
+                            osg::ref_ptr<osgUtil::IncrementalCompileOperation::CompileSet> compileSet = 
+                                new osgUtil::IncrementalCompileOperation::CompileSet(loadedModel.get());
+
+                            compileSet->_compileCompletedCallback = new ReleaseBlockOnCompileCompleted(_endOfLoadBlock.get());
+
+                            _incrementalCompileOperation->add(compileSet.get());
+                        }
+                        else
+                        {
+                            _endOfLoadBlock->completed();
                         }
                     }
-                }
+                    else
+                    {
+                        _endOfLoadBlock->completed();
+                    }
+                }
+
+                _endOfLoadBlock->block();
+
             }
                         
-            if (requiresBarrier)
-            {
-                _endOfCompilebarrier = new osg::BarrierOperation(threads.size()+1);
-                _endOfCompilebarrier->setKeep(false);
-                
-                for(GraphicsThreads::iterator gitr = threads.begin();
-                    gitr != threads.end();
-                    ++gitr)
-                {
-                    (*gitr)->add(_endOfCompilebarrier.get());
-                }
-                
-                // osg::notify(osg::NOTICE)<<"Waiting for Compile to complete"<<std::endl;
-
-                // wait for the graphics threads to complete.
-                _endOfCompilebarrier->block();
-                
-                // osg::notify(osg::NOTICE)<<"done ... Waiting for Compile to complete"<<std::endl;
-            }
         }
         
@@ -455,4 +468,5 @@
     OpenThreads::Block                  _updatesMergedBlock;
 
+    osg::ref_ptr<osgUtil::IncrementalCompileOperation>  _incrementalCompileOperation;
     osg::ref_ptr<osg::BarrierOperation> _endOfCompilebarrier;
     osg::ref_ptr<osg::RefBlockCount>    _endOfLoadBlock;
@@ -619,4 +633,7 @@
     viewer.addEventHandler(new osgViewer::RecordCameraPathHandler);
 
+    // attach an IncrementaCompileOperation to allow the master loading 
+    // to be handled with an incremental compile to avoid frame drops when large objects are added.
+    viewer.setIncrementalCompileOperation(new osgUtil::IncrementalCompileOperation());
 
     double x = 0.0;
@@ -632,5 +649,5 @@
     while(arguments.read("-m",masterFilename))
     {
-        masterOperation = new MasterOperation(masterFilename);
+        masterOperation = new MasterOperation(masterFilename, viewer.getIncrementalCompileOperation());
     }