Recently our team converted to Visual Studio 2005 and it has been v e r y s l o w. Builds are 3x slower, switching to design mode of a .ascx page takes 30+ secs...it has been very painful.
I sent an email to Scott Guthrie who pointed me to a hot fix that is available by calling Microsoft Support if you are experiencing the same issue.
http://support.microsoft.com/default.aspx?scid=kb;EN-US;920805
This hot fix will be rolled up into Visual Studio 2005 Service Pack 1 (no word on an official date). I hadn't heard about the hot fix, so I wanted to pass on the info.