Anyone know of any good references as to what sort of optimisations the /o+ switch enables?

Over the weekend I was somewhat surprised at the (low) level of optimisation I was getting in the generated IL, given that the managed environment means that so much more is guaranteed than in the unmanaged world. One possible explanation that is that some of it is put off until the JIT compilation phase - I guess I'll have to use NGEN and see what I can make of the resultant assembler.

I'll try to knock my code fragments and the resultant IL into some sort of shape and post them back here as soon as I get the chance...

UPDATE: The C# and IL snippets are now here. Any thoughts, advice, comments, etc. would be most welcome.