There were a lot of question on good reference material for .NET (books and online). Here is a consolidated list of resources I am aware of. If anyone knows of more stuff – please do feel free to suggest in the comments.

1. CLR and JIT
   1. CLR via C#, Second Edition (Pro Developer) By Jeffrey Richter
   2. Drill Into .NET Framework Internals to See How the CLR Creates Runtime Objects

      http://msdn.microsoft.com/msdnmag/issues/05/05/JITCompiler/

       

2. NGEN
   1. NGen Revs Up Your Performance with Powerful New Features

      http://msdn.microsoft.com/msdnmag/issues/05/04/NGen/default.aspx

   2. The Performance Benefits of NGen.

      http://msdn.microsoft.com/msdnmag/issues/06/05/CLRInsideOut/

       

3. Garbage Collection
   1. Garbage Collection—Part 1: Automatic Memory Management in the Microsoft .NET Framework - Jeffery Richter

      http://msdn.microsoft.com/msdnmag/issues/1100/GCI/default.aspx

   2. Garbage Collection—Part 2: Automatic Memory Management in the Microsoft .NET Framework - Jeffery Richter

      http://msdn.microsoft.com/msdnmag/issues/1200/GCI2/default.aspx

   3. Garbage Collector Basics and Performance Hints - Rico Mariani

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

      this link is broken as of now – I will update the post if I get the new location – but I will strongly recommend you to follow Rico's blog for GC and performance details.

   4. Cleaning Up Unmanaged Resources    

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

   5. Programming for Garbage Collection

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

   6. Garbage collection and resource deallocation

      http://www.thecodeproject.com/csharp/gcresdealloc.asp

   7. Roadmap for garbage collection in the Microsoft .NET Framework

      http://support.microsoft.com/default.aspx?scid=kb;en-us;317866

   8. OverView of GC:

      http://msdn.microsoft.com/msdnmag/issues/1100/GCI/default.aspx

   9. .NET GC Myth #2 -- The GC Frees Memory

      http://weblogs.asp.net/pwilson/archive/2004/02/20/77429.aspx

   10. Using GC Efficiently – Part 2

       http://blogs.msdn.com/maoni/archive/2004/09/25/234273.aspx

   11. OutOfMemoryException and Pinning

       https://blogs.msdn.com/yunjin/archive/2004/01/27/63642.aspx

        

4. Managed Code/IL/Assembly
   1. http://blogs.msdn.com/trobbins/articles/404939.aspx
   2. Inside Microsoft .NET IL Assembler by Serge Lidin

       

5. Feature difference between 2.0 and 3.0
   1. The best site I know that can serve as a starting point to understand new features and developments in .NET 3.0 and .NET 3.5 is

      http://www.netfx3.com/

       

6. Understanding differences of the Native and Managed worlds
   1. Migrating Native Code to the .NET CLR

      http://msdn.microsoft.com/msdnmag/issues/01/05/com/