diff --git a/Effects/EffectHelpers.cs b/Effects/EffectHelpers.cs
new file mode 100644
index 0000000..e2618cb
--- /dev/null
+++ b/Effects/EffectHelpers.cs
@@ -0,0 +1,14 @@
+using System;
+
+namespace Smuggler
+{
+    [Flags]
+    internal enum EffectDirtyFlags
+    {
+        WorldViewProj = 1,
+        World = 2,
+        EyePosition = 4,
+        ShaderIndex = 8,
+        All = -1
+    }
+}
\ No newline at end of file
diff --git a/Effects/PBREffect.cs b/Effects/PBREffect.cs
index 025d05c..eec2796 100644
--- a/Effects/PBREffect.cs
+++ b/Effects/PBREffect.cs
@@ -83,6 +83,8 @@ namespace Smuggler
         bool metallicRoughnessMapEnabled = false;
         bool normalMapEnabled = false;
 
+        EffectDirtyFlags dirtyFlags= EffectDirtyFlags.All;
+
         // FIXME: lazily set properties for performance
 
         public Matrix World
@@ -91,15 +93,7 @@ namespace Smuggler
             set 
             { 
                 world = value;
-                worldParam.SetValue(world);
-
-                Matrix.Multiply(ref world, ref view, out Matrix worldView);
-                Matrix.Multiply(ref worldView, ref projection, out Matrix worldViewProj);
-                worldViewProjectionParam.SetValue(worldViewProj);
-
-                Matrix.Invert(ref world, out Matrix worldInverse);
-                Matrix.Transpose(ref worldInverse, out Matrix worldInverseTranspose);
-                worldInverseTransposeParam.SetValue(worldInverseTranspose);
+                dirtyFlags |= EffectDirtyFlags.World | EffectDirtyFlags.WorldViewProj;
             }
         }
 
@@ -109,13 +103,7 @@ namespace Smuggler
             set 
             { 
                 view = value;
-
-                Matrix.Multiply(ref world, ref view, out Matrix worldView);
-                Matrix.Multiply(ref worldView, ref projection, out Matrix worldViewProj);
-                worldViewProjectionParam.SetValue(worldViewProj);          
-                
-                Matrix.Invert(ref view, out Matrix inverseView);
-                eyePositionParam.SetValue(inverseView.Translation);
+                dirtyFlags |= EffectDirtyFlags.WorldViewProj | EffectDirtyFlags.EyePosition;
             }
         }
 
@@ -125,10 +113,7 @@ namespace Smuggler
             set 
             { 
                 projection = value;
-
-                Matrix.Multiply(ref world, ref view, out Matrix worldView);
-                Matrix.Multiply(ref worldView, ref projection, out Matrix worldViewProj);
-                worldViewProjectionParam.SetValue(worldViewProj);   
+                dirtyFlags |= EffectDirtyFlags.WorldViewProj;
             }
         }
 
@@ -185,7 +170,7 @@ namespace Smuggler
             { 
                 albedoTextureParam.SetValue(value); 
                 albedoTextureEnabled = value != null;
-                System.Console.WriteLine(albedoTextureEnabled);
+                dirtyFlags |= EffectDirtyFlags.ShaderIndex;
             }
         }
 
@@ -196,6 +181,7 @@ namespace Smuggler
             { 
                 normalTextureParam.SetValue(value);
                 normalMapEnabled = value != null;
+                dirtyFlags |= EffectDirtyFlags.ShaderIndex;
             }
         }
 
@@ -218,6 +204,7 @@ namespace Smuggler
             { 
                 metallicRoughnessTextureParam.SetValue(value);
                 metallicRoughnessMapEnabled = value != null;
+                dirtyFlags |= EffectDirtyFlags.ShaderIndex;
             }
         }
 
@@ -287,41 +274,73 @@ namespace Smuggler
             return new PBREffect(this);
         }
 
-        // FIXME: do param applications here for performance
         protected override void OnApply()
         {
-            int shaderIndex = 0;
+            if ((dirtyFlags & EffectDirtyFlags.World) != 0)
+            {
+                worldParam.SetValue(world);
 
-            if (albedoTextureEnabled && metallicRoughnessMapEnabled && normalMapEnabled)
-            {
-                shaderIndex = 7;
-            }
-            else if (metallicRoughnessMapEnabled && normalMapEnabled)
-            {
-                shaderIndex = 6;
-            }
-            else if (albedoTextureEnabled && normalMapEnabled)
-            {
-                shaderIndex = 5;
-            }
-            else if (albedoTextureEnabled && metallicRoughnessMapEnabled)
-            {
-                shaderIndex = 4;
-            }
-            else if (normalMapEnabled)
-            {
-                shaderIndex = 3;
-            }
-            else if (metallicRoughnessMapEnabled)
-            {
-                shaderIndex = 2;
-            }
-            else if (albedoTextureEnabled)
-            {
-                shaderIndex = 1;
+                Matrix.Invert(ref world, out Matrix worldInverse);
+                Matrix.Transpose(ref worldInverse, out Matrix worldInverseTranspose);
+                worldInverseTransposeParam.SetValue(worldInverseTranspose);
+
+                dirtyFlags &= ~EffectDirtyFlags.World;
             }
 
-            shaderIndexParam.SetValue(shaderIndex);
+            if ((dirtyFlags & EffectDirtyFlags.WorldViewProj) != 0)
+            {
+                Matrix.Multiply(ref world, ref view, out Matrix worldView);
+                Matrix.Multiply(ref worldView, ref projection, out Matrix worldViewProj);
+                worldViewProjectionParam.SetValue(worldViewProj);
+
+                dirtyFlags &= ~EffectDirtyFlags.WorldViewProj;
+            }
+
+            if ((dirtyFlags & EffectDirtyFlags.EyePosition) != 0)
+            {
+                Matrix.Invert(ref view, out Matrix inverseView);
+                eyePositionParam.SetValue(inverseView.Translation);
+
+                dirtyFlags &= ~EffectDirtyFlags.EyePosition;
+            }
+
+            if ((dirtyFlags & EffectDirtyFlags.ShaderIndex) != 0)
+            {
+                int shaderIndex = 0;
+
+                if (albedoTextureEnabled && metallicRoughnessMapEnabled && normalMapEnabled)
+                {
+                    shaderIndex = 7;
+                }
+                else if (metallicRoughnessMapEnabled && normalMapEnabled)
+                {
+                    shaderIndex = 6;
+                }
+                else if (albedoTextureEnabled && normalMapEnabled)
+                {
+                    shaderIndex = 5;
+                }
+                else if (albedoTextureEnabled && metallicRoughnessMapEnabled)
+                {
+                    shaderIndex = 4;
+                }
+                else if (normalMapEnabled)
+                {
+                    shaderIndex = 3;
+                }
+                else if (metallicRoughnessMapEnabled)
+                {
+                    shaderIndex = 2;
+                }
+                else if (albedoTextureEnabled)
+                {
+                    shaderIndex = 1;
+                }
+
+                shaderIndexParam.SetValue(shaderIndex);
+
+                dirtyFlags &= ~EffectDirtyFlags.ShaderIndex;
+            }
         }
 
         void CacheEffectParameters(PBREffect cloneSource)