The HTML editor in VS2008 was killing me on pages using the fancier DevExpress controls. The editor would freeze after every keystroke. Responsiveness was so bad I started using a plain text editor to make changes to those pages.
Thankfully, a hotfix is now publically available. I tested an early version of the hotfix, and it made Visual Studio 2008 a happy place to work in again.
This wasn't a problem with the DevExpress controls, by the way. Their controls get better and better with each release. My recent favorite is the ASPxPivotGrid, which can slice and dice data from a relational database, or an OLAP database. Try the online demos for yourself.