This announcement applies to all Windows 8 developers who are using Visual Studio 11 to experiment and develop WinRT applications. As of April 10, 2012, there is an update available for Visual Studio 11 Beta.
According to the official release notes, this update improves the stability of the IDE - there are a couple of fixes applied to the visual XAML designer, the Razor file editor and some some generic IDE components. Performance-wise, this update is primarily targeting C# developers, who will no longer experience long delays when trying to scroll in a C# file after opening it as well as the freeze that previously occured when typing in C# projects that implement SupportAsyncPattern.
Additional fixes cover Team Explorer, C++ projects and the Visual Studio extensibility layer.
If you have Windows 8 installed, but don't have Visual Studio 11 Beta yet, download it here.