In the last days I struggled with the Visual Studio 2005 editor becoming extremely slow. Simply moving the cursor to the end of a line with 120 characters by holding down the right arrow key could take up to 5 seconds. VS2008 running in a VM under Linux was much faster.

I finally found the solution in an old thread at microsoft.public.dotnet.languages.csharp:

devenv.exe /resetuserdata

Not sure, what kind of setting was causing this slowness, but resetting to the defaults helped.