Optimising Groovy bytecodes with Soot

I'm playing around Soot framework and get some optimised bytecodes after applying its default optimisation to Groovy-generated classes.
This does not help much for speed improvement, but I think it could help reduce the usage of PermGen space.

I've tested with a trivial class, and its file size after optimisation is 8.5% shrinker than the original. I'm expecting that this figure would be large if we optimise a whole application.