Im not sure since I dont have Pro, but I THINK it also relies on Flash Player.  So my guess (assuming this to be true) is that if the Poser 8 freezes were caused by other programs running Flash Player, then you should also get similar freezes in Pro.

Im not trying to jinx you there, but if you DO get freezes in Pro as well, then still do what I had just mentioned.  (about looking for other programs using Flash Player).
Still, good luck softcris :)