Over the last year we've seen several people report having performance problems when using F5 to run/debug ASP.NET 2.0 applications using Visual Studio 2005. The problem in theses cases typically wasn't with building the project, but rather that it sometimes took the debugger a really long time to hit the first breakpoint once it attached to the application (45+ seconds and longer sometimes).
We recently posted a public hotfix patch that you can download and apply to fix this issue. You can download the hotfix immediately here. You can read more about it in this KB article here.
Background on the Issue
The particular bug fixed in this hotfix was surprisingly difficult to track down. The slowdown issue occurred when breakpoints were set in multiple source files in the same project that had the same short file names (for example: two default.aspx.cs files) and which were organized in a certain directory structure pattern on disk. The patch fixes this issue and should prevent the debugger from pausing when trying to load the web project's assembly symbols in this case.
For Technical Support with this Patch
If you have any problems installing the patch or find that you still see issues after you install it, you'll want to contact Microsoft product support for assistance and they'll help debug it further. Calls to Microsoft Product Support are free if they are related to a product bug (either a QFE HotFix request or a product bug you are running into). You can find details on how to contact Microsoft product support on this page (it allows you to lookup the local phone number to use by country).
Other Hotfix Patches
I've posted in the past about other ASP.NET and VS related hotfix patches that can be publicly downloaded. Here are a few pointers to these posts:
More Performance and Tip/Tricks/Tutorial Posts
Make sure to check out my Tip/Trick: Optimizing ASP.NET 2.0 Web Project Build Performance with VS 2005 post if you have build performance issues with VS 2005.
Please visit and bookmark my ASP.NET 2.0 Tips, Tricks, Recipes, and Gotchas page for a good listing of some of my previous ASP.NET and Visual Studio posts and tutorials.
Hope this helps,