This was released about a year ago, but still some valuable information on ASP.NET perf tuning:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnpag/html/scalenetchapt17.asp

"This chapter provides an iterative process to systematically identify, tune, and eliminate bottlenecks until your application meets its performance objectives. The chapter covers tuning the ASP.NET thread pool for various scenarios, including burst load and COM interop . It also shows you how to tune timeouts such as session timeouts, script timeouts, execution timeout and deadlock intervals. It also explains how to tune Web gardens, the Enterprise Services object pool, and much more."