Redgate just released a free ASP.NET eBook which contains 50 highly condensed, and highly practical, ASP.NET performance tips spanning a number of related topics; ORM, MVC, LINQ, SQL, async, string manipulation etc. Worth mentioning is that all of the tips came from developers in the .NET community.
The eBook can be downloaded in PDF format, and all it requires is your name, email and a number.
I’m a big fan of reading abbreviated “best of” tips on any framework in the Microsoft web stack and was quite impressed with the content and it’s presentation. I’d highly recommend this to any junior to intermediate-level ASP.NET developers.