Mono Software Web Application Optimizer
This is a great tool to throw onto your website. For example I had a RadToolstrip which contained a few usercontrols, and some ajax going on. The result was a 161k page, posting back to the server and as you can well imagine this was SUPER laggy. Throwing WAO in there I was able to drop the size to 28k! I'm a huge fan of being able to remove viewstate from the page equation...which really is where ASP.Net fails on the performance end. Give it a try, $99 for a domain license, crazy good deal. (no affiliation, just thought it'd be handy for someone)