Here is a list of Optimization and Performance links:

Improving .NET Application Performance and Scalability
Best SQL Server Performance Tuning Tips
Changes to Performance Monitor Web Service Counters in IIS 6.0
Improving .NET Application Performance and Scalability, Chapter 6 “Improving ASP.NET Performance

Full list of all app blocks: http://www.microsoft.com/resources/practices/code.mspx

Improved Caching in ASP.NET 2.0