Dopo avere installato Visual Studio 2010 Beta2 è possibile migliorare le performance del designer WPF/Silverlight modificando il registry in questo modo:
1. Close any open VS instances
2. Open RegEdit (as an administrator as needed)
3. Select the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\VisualStudio\10.0 key
4. Right click and add key, type ClrHost
5. In the newly created key, right click and add a DWORD32 with the name StartupFlags
6. Set its value to 5
7. Close RegEdit
8. Start up Visual Studio and use as normal
Fonte: http://bit.ly/1RymVU