I love comparing current trunk against 0.9.0. It always makes me happy.
Here are the numbers for a local gem install rake. The second set of numbers is trunk plus a ThreadContext-passing experimental patch I'm working on. Without my experimental patch, trunk benchmarks about four seconds slower.
trunk + my patch:
That's an increase of 32%. Are we having fun yet?
The best part of this is that we haven't even started on a number of very promising performance changes, and we're still not compiling anything. Nibbling, nibbling away at overhead is paying serious dividends.