We shipped MVC4 Beta recently, and found it may cause VS2010 sp1 cshtml/vbhtml editor to pause for a long time after typing snippet, JavaScript inside cshtml or vbhtml files, if the MVC4 application has just been created and has not been compiled.

The workaround is to compile the project to get the assemblies in the bin folder.  Note, if you clean the project which removes the assemblies from the bin folder, the editor problem will come back.

We are actively working on a resolution for this issue for next release.  Thanks.

Best regards.

Xinyang Qiu

Web Platform and Tools Team

3/6/2012 update: If you meet VS 11 Beta razor editor crash issue, please check http://blogs.msdn.com/b/webdevtools/archive/2012/03/06/visual-studio-11-beta-razor-editor-issue-workaround.aspx.