Often when testing the performance of a ASP.Net website you need to see how the site will perform under extreme conditions. This is easy to do in a virtual environment where you can reduce the number of CPUs or available RAM.

But how do you test this on a physical box?

Vijayshinva Karnure has written a short list of tools that you can use to stress out the CPU, Memory and Disk outside of your ASP.Net application so you can look for memory / timeout / response problems

Check out the list here http://blogs.msdn.com/b/vijaysk/archive/2012/10/27/tools-to-simulate-cpu-memory-disk-load.aspx

A number of these tools come from the Windows SysInternals team who are all about performance