diff --git a/include/osgUtil/CullVisitor b/include/osgUtil/CullVisitor
index 5e79f7e67..39ab2351c 100644
--- a/include/osgUtil/CullVisitor
+++ b/include/osgUtil/CullVisitor
@@ -197,6 +197,47 @@ class OSGUTIL_EXPORT CullVisitor : public osg::NodeVisitor
             return _eyePointStack.back();
         }
 
+
+        inline float pixelSize(const osg::Vec3& v, float const radius)
+        {
+            const osg::Matrix& mvpw = getMVPW();
+            if (_windowToModelFactorDirty)
+            {
+                _windowToModelFactorDirty=false;
+                _windowToModelFactor = osg::Vec3(mvpw(0,0),mvpw(1,0),mvpw(2,0)).length();
+            }
+            float W = v.x()*mvpw(0,3)+
+                      v.y()*mvpw(1,3)+
+                      v.z()*mvpw(2,3)+
+                            mvpw(3,3);
+                                 
+            return fabs(radius*_windowToModelFactor/W);
+        }
+
+
+        inline bool isCulled(const osg::BoundingSphere& sp,CullingMode& mode)
+        {
+            if (!sp.isValid()) return true;
+
+            if (!(_modelviewClippingVolumeStack.back().contains(sp,mode))) return true;
+
+            if (mode&SMALL_FEATURE_CULLING)
+            {
+                if (pixelSize(sp.center(),sp.radius())<_smallFeatureCullingPixelSize) return true;
+            }
+            return false;
+        }
+
+        inline const bool isCulled(const osg::BoundingBox& bb,CullingMode mode)
+        {
+            if (!bb.isValid()) return true;
+
+            return !_modelviewClippingVolumeStack.back().contains(bb,mode);
+        }
+        
+        void setSmallFeatureCullingPixelSize(float s) { _smallFeatureCullingPixelSize=s; }
+        float getSmallFeatureCullingPixelSize() const { return _smallFeatureCullingPixelSize; }
+
     protected:
 
         /** prevent unwanted copy construction.*/
@@ -233,30 +274,6 @@ class OSGUTIL_EXPORT CullVisitor : public osg::NodeVisitor
         }
 
 
-        inline bool isCulled(const osg::BoundingSphere& sp,CullingMode& mode) const
-        {
-            if (!sp.isValid()) return true;
-
-            if (!(_modelviewClippingVolumeStack.back().contains(sp,mode))) return true;
-
-            if (mode&SMALL_FEATURE_CULLING)
-            {
-                const float _ratio2 = 0.002f*0.002f;
-                osg::Vec3 delta(sp._center-getEyeLocal());
-                if (sp.radius2()<delta.length2()*_ratio2)
-                {
-                    return true;
-                }
-            }
-            return false;
-        }
-
-        inline const bool isCulled(const osg::BoundingBox& bb,CullingMode mode) const
-        {
-            if (!bb.isValid()) return true;
-
-            return !_modelviewClippingVolumeStack.back().contains(bb,mode);
-        }
 	
 	void updateCalculatedNearFar(const osg::Matrix& matrix,const osg::Drawable& drawable);
     	void updateCalculatedNearFar(const osg::Vec3& pos);
@@ -356,7 +373,9 @@ class OSGUTIL_EXPORT CullVisitor : public osg::NodeVisitor
             {
                 if (!_MVPW_Stack.back())
                 {
-                    _MVPW_Stack.back() = new osg::Matrix(getModelViewMatrix()*getProjectionMatrix()*getWindowMatrix());
+                    _MVPW_Stack.back() = createOrReuseMatrix(getModelViewMatrix());
+                    (*_MVPW_Stack.back()) *= getProjectionMatrix();
+                    (*_MVPW_Stack.back()) *= getWindowMatrix();
                 }
                 return *_MVPW_Stack.back();
             }
@@ -381,7 +400,10 @@ class OSGUTIL_EXPORT CullVisitor : public osg::NodeVisitor
         MatrixStack                                         _modelviewStack;
         MatrixStack                                         _MVPW_Stack;
         ClippingVolumeStack                                 _modelviewClippingVolumeStack;
-
+        
+        bool                                                _windowToModelFactorDirty;
+        float                                               _windowToModelFactor;
+                
         typedef std::vector<osg::ref_ptr<osg::Viewport> >   ViewportStack;
         ViewportStack                                       _viewportStack;
         
@@ -404,7 +426,7 @@ class OSGUTIL_EXPORT CullVisitor : public osg::NodeVisitor
 
 
         float   _LODBias;
-
+        float   _smallFeatureCullingPixelSize;
 
         enum ComputeNearFarMode
         {
@@ -430,7 +452,7 @@ class OSGUTIL_EXPORT CullVisitor : public osg::NodeVisitor
 	MatrixList _reuseMatrixList;
 	unsigned int _currentReuseMatrixIndex;
 	
-	inline osg::Matrix* createOrReuseMatrix(const osg::Matrix value)
+	inline osg::Matrix* createOrReuseMatrix(const osg::Matrix& value)
 	{
             // skip of any already reused matrix.
             while (_currentReuseMatrixIndex<_reuseMatrixList.size() && 
diff --git a/src/osgUtil/CullVisitor.cpp b/src/osgUtil/CullVisitor.cpp
index a29bc6f27..8ec4b237d 100644
--- a/src/osgUtil/CullVisitor.cpp
+++ b/src/osgUtil/CullVisitor.cpp
@@ -105,6 +105,10 @@ CullVisitor::CullVisitor()
     _numFramesToKeepImpostorSprites = 10;
     _impostorSpriteManager = osgNew ImpostorSpriteManager;
 
+    _windowToModelFactorDirty = true;
+    _windowToModelFactor = 1.0f;
+    _smallFeatureCullingPixelSize = 3.0f;
+
 }
 
 
@@ -159,6 +163,8 @@ void CullVisitor::reset()
         (*itr)->reset();
     }
     
+    _windowToModelFactorDirty = true;
+    _windowToModelFactor = 1.0f;
 }
 
 void CullVisitor::pushClippingVolume()
@@ -167,12 +173,16 @@ void CullVisitor::pushClippingVolume()
     if (!_modelviewStack.empty()) _modelviewClippingVolumeStack.back().transformProvidingInverse(*_modelviewStack.back());
 
     _MVPW_Stack.push_back(0L);
+
+    _windowToModelFactorDirty = true;
 }
 
 void CullVisitor::popClippingVolume()
 {
     _modelviewClippingVolumeStack.pop_back();
     _MVPW_Stack.pop_back();
+
+    _windowToModelFactorDirty = true;
 }
 
 void CullVisitor::pushViewport(osg::Viewport* viewport)
@@ -436,6 +446,37 @@ void CullVisitor::apply(Geode& node)
         }
 
     }
+//     osg::Timer timer;
+//     osg::Timer_t ta = timer.tick();
+//     const osg::Matrix& mvpw = getMVPW();
+//     osg::Timer_t tb = timer.tick();
+// 
+//     const osg::BoundingSphere& sp = node.getBound();
+//     osg::Vec3 v = sp._center;
+//     float radius = sp._radius;
+//     osg::Timer_t t1 = timer.tick();
+//     bool result1 = pixelSize(v,sp.radius())<4.0f;
+//     osg::Timer_t t2 = timer.tick();
+//     
+//     const float _ratio2 = 0.002f*0.002f;
+//     osg::Vec3 delta(v-getEyeLocal());
+//     bool result2 = (sp.radius2()<delta.length2()*_ratio2);
+// 
+//     osg::Timer_t t3 = timer.tick();
+// 
+//     float W = v.x()*mvpw(0,3)+
+//               v.y()*mvpw(1,3)+
+//               v.z()*mvpw(2,3)+
+//                     mvpw(3,3);
+// 
+//     bool result3 = fabs(radius*_windowToModelFactor/W);
+// 
+//     osg::Timer_t t4 = timer.tick();
+//     
+//     cout << "time pixelSize = "<<t2-t1<<endl;
+//     cout << "     odl       = "<<t3-t2<<endl;
+//     cout << "     stripped  = "<<t4-t3<<endl;
+//     cout << "     getMVPW   = "<<tb-ta<<endl;
 
     // pop the node's state off the geostate stack.    
     if (node_state) popStateSet();