It's not choppy at all for me, it's silk smooth (except for some parts where there are too many things on screen in wich it goes a little slow, but not choppy at all)... but believe it or not it does not have to do with the machine (no matter if you have a quad or a core 2... the game will run exactly the same (as the emulator has no compatibility for more than 2 cores)
carefull tough r4681m WAS choppy (but just that revision, 4682 works fine)
carefull tough r4681m WAS choppy (but just that revision, 4682 works fine)