Spring, my old friend

http://highscalability.com/blog/2012/5/2/12-ways-to-increase-throughput-by-32x-and-reduce-latency-by.html

Keep call stacks reasonably small.  Still more work to do here.  If you are crazy enough to use Spring, then check out your call stacks to see what I mean!  The garbage collector has to walk them finding reachable objects.