As I noted earlier, last week the entire CLR team went through many hours of training on how to write faster managed code.  One of the presentations I caught was from one of our folks in the field how gets to debug perf issues on live, mission critical servers running ASP.NET (or other managed code solutions).  

She showed a lot of neat tricks and I just found out her team published many of them publicly!  Have fun.

 

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnbda/html/DBGrm.asp