Thanks for the version info.
Please do try removing the "stub_optimize" flag, and let us know how it goes.
BTW, we're about to release (early next week, if not this week) 6.1.1 and 6.0.2 maintenance releases, and they do have some improvements in this very area, so you may want to try it out when it's out. If you're going to go to 6.1, you'll need a new license (free upgrade if you're on support), so please be aware.
-shinya.