I've been reading a great book, Improving .Net Application Performance and Scalability. While I'm aware of the standard performance issues (minimize calls to the database, reduce postbacks, cache, use client validation, DataReader vs. DataSet, etc...), I've really been impressed with the book so far. It's about a 1000 pages, and is very thorough yet practical.
I admit that I was surprised at the resourcefulness of some of their suggestions, such as how to improve ASP.Net performance by trimming page size:
- Remove unnecessary white space between tags
- Avoid long control names (it gets rendered into HTML)
They also suggest several tools to help monitor performance: