Microsoft released a hotfix  for Visual Studio 2008 (also targeting Visual Web Developer Express) that corrects several issues with the web development features.
At this time the hotfix is only available for the English and Japanese versions.
List of things that were corrected according to this post  by Vinaya Reddy:
HTML Source view performance
- Source editor freezes for a few seconds when typing in a page with a custom control that has more than two levels of sub-properties.
- “View Code” right-click context menu command takes a long time to appear with web application projects.
- Visual Studio has very slow behavior when opening large HTML documents.
- Visual Studio has responsiveness issues when working with big HTML files with certain markup.
- The Tab/Shift-Tab (Indent/Un-indent) operation is slow with large HTML selections.
Design view performance
- Slow typing in design view with certain page markup configurations.
- Quotes are not inserted after Class or CssClass attribute even when the option is enabled.
- Visual Studio crashes when ServiceReference element points back to the current web page.
Web Site build performance
- Build is very slow when Bin folder contains large number of assemblies and .refresh files with web-site projects.
Make sure to read the installation instructions at .