I see...with your example code, i can reproduce the problem. It's a memory leak in the visibility list management. However, there is no workaround ATM, so you've to live with that until the new version is final (next week, i hope). I'll add a fix to that version. Unfortunately i have to add a dispose()-method to World to fix this. I'll also add it to finalize(), which may help to fix this for older applications, but as we all know, finalize() shouldn't be used for such things, because...blah...blah....i'll add it anyway.
Thanks for pointing this out.