hack to clear window context, and only call interopsurface.resize when size actually changes.

src/Windows/Avalonia.Win32/Composition/CompositionHost.cs

@@ -51,13 +51,42 @@ namespace Avalonia.Win32
 
             public override bool IsCorrupted => _initialSize != _info.Size;
 
+            bool _firstRun = true;
+            POINT lastSize;
             public override IGlPlatformSurfaceRenderingSession BeginDraw()
             {
+                if (_firstRun)
+                {
+                    _firstRun = false;
+                    var windowSurface = new EglGlPlatformSurface(Win32GlManager.EglFeature.DeferredContext, _info);
+
+                    using (var target = windowSurface.CreateGlRenderTarget())
+                    {
+                        using (var session = target.BeginDraw())
+                        {
+                            using (session.Context.MakeCurrent())
+                            {
+                                var gl = _context.GlInterface;
+                                gl.Viewport(0, 0, _info.Size.Width, _info.Size.Height);
+                                gl.ClearStencil(0);
+                                gl.ClearColor(0, 0, 0, 0);
+                                gl.Clear(GlConsts.GL_COLOR_BUFFER_BIT | GlConsts.GL_DEPTH_BUFFER_BIT);
+                                gl.Flush();                                
+                            }
+                        }
+                    }
+                }
+
+
                 var iid = Guid.Parse("6f15aaf2-d208-4e89-9ab4-489535d34f9c");
                 var updateRect = new RECT { right = _info.Size.Width, bottom = _info.Size.Height };
                 var offset = new POINT();
 
-                _surfaceInterop.Resize(new POINT { X = _info.Size.Width, Y = _info.Size.Height });
+                if (lastSize.X != _info.Size.Width || lastSize.Y != _info.Size.Height)
+                {
+                    lastSize = new POINT { X = _info.Size.Width, Y = _info.Size.Height };
+                    _surfaceInterop.Resize(lastSize);
+                }                
                 _surfaceInterop.BeginDraw(
                     ref updateRect,
                     ref iid,
@@ -65,7 +94,7 @@ namespace Avalonia.Win32
 
                 var surface = (_display as AngleWin32EglDisplay).WrapDirect3D11Texture(texture);
 
-                return base.BeginDraw(surface, _info, () => { _surfaceInterop.EndDraw(); }, true);
+                return base.BeginDraw(surface, _info, () => { _surfaceInterop.EndDraw(); Marshal.Release(texture); surface.Dispose();  }, true);
             }
         }
     }

src/Windows/Avalonia.Win32/Composition/GaussianBlurEffect.cs

@@ -52,7 +52,7 @@ namespace Avalonia.Win32
                     return 30.0f;
 
                 case D2D1GaussianBlurProp.D2D1_GAUSSIANBLUR_PROP_OPTIMIZATION:
-                    return (UInt32)D2D1_GAUSSIANBLUR_OPTIMIZATION.D2D1_GAUSSIANBLUR_OPTIMIZATION_SPEED;
+                    return (UInt32)D2D1_GAUSSIANBLUR_OPTIMIZATION.D2D1_GAUSSIANBLUR_OPTIMIZATION_BALANCED;
 
                 case D2D1GaussianBlurProp.D2D1_GAUSSIANBLUR_PROP_BORDER_MODE:
                     return (UInt32)D2D1_BORDER_MODE.D2D1_BORDER_MODE_HARD;

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -100,7 +100,9 @@ namespace Avalonia.Win32
             _framebuffer = new FramebufferManager(_hwnd);
 
             if (Win32GlManager.EglFeature != null)
+            {                
                 _gl = new CompositionEglGlPlatformSurface(Win32GlManager.EglFeature.DeferredContext, this);
+            }
 
             if (_gl is CompositionEglGlPlatformSurface cgl)
             {