I had a terrible experience with VS2008. Although I use a speedy Quad Core CPU, 4 GB of RAM, fast hard drives and a fast graphic card - it took between 5 and 10 seconds to redraw a form in Visual Studio designer. I wasn’t sure if it’s because of the excellent DevExpress components we use for all our .NET products, but it seemed just a bit too much to expect, even from Microsoft.
So, after being fed up with the sluggish VS interface once too much, I googled to see if there is a solution. Guess what? I found it in just a few minutes and am not cursing VS anymore. Because of this issue, at least. 
In short, if your problem is caused by the same thing that slowed me down, just go to Internet Options (either from Control Panel or from IE’s Tools menu) and uncheck the Check for publisher’s certificate revocation* in the Advanced tab, under Security Node section in the tree list.
Read the whole thread here:
http://social.msdn.microsoft.com/Forums/en-US/vssetup/thread/bc778e26-9156-4924-a9ca-a57ef8ff6bcc