If you're running Visual Studio 2010 on XP or Vista you may benefit from installing this upgrade: http://support.microsoft.com/kb/981741 Applications that use Windows Automation APIs can significantly decrease Microsoft Visual Studio IntelliSense performance if Windows Automation API 3.0 is not installed...

Brian Harry has posted a discussion of Intellisense performance improvements in VS2010 that we've made since Beta 2, including bothe before and after videos. He also touches a little on the massive performance effort we're making as a division to address the performance issues identified by our external...