The CLR team has a couple of slides from their roadshow where they talk about two tracks, one discusses what happens insight the CLR, if you have some of the books recommended in the presentation, none of this would be new to you. It covers things like the IL which is the abstract representation of an execution semantic and how that is represented using an abstract stack machine, where we consecutively execute each instruction, using the stack as the evaluation of that execution and how this stack abstraction works. And two, there is a discussion on perf engineering including the GC, costs and pitfalls, etc.
On a different note, been out and about on a few days of holiday with family visiting, but its good to be back now. :)