Hmm, I'd say it dropped to about a 5-10 FPS crawl. It popped right back up once I spun the camera so all the spell effects weren't on screen at once. Admittedly that is not ideal in a battle situation, but really hasn't caused me much issue.
The framerate only dropped that low on me a couple of times, though. So I'd say it's worst case.
But yeah, if you prefer the better framerate, 360 would be the best option. Unless you have more friends on the PS3 whose pawns you'd like to use, then it really isn't that bad.
I wonder if/when there will be a side by side comparison of the retail version.
5-10!?
Fuck my life, what the hell developers
I guess I'll just... not use magic >_<