turn off cglib.use_reflection_optimizer
There are lots of post online about Hibernate permgem error, and sounds like there is not much one can do, other than include permgen space, since the problem most likely not in your code, but in Hibernate.
I saw one interesting suggestion yesterday: to turn off cglib reflection optimization. But the author at the same time said that this might lower performance. Have anyone actually tried this before? What's the result?