Framerate still suffers, particularly in the first level, but yes it really does help tremendously. My guess is that the resolution changes that the game seems to employ are affected by the camera somewhat. Speeding the camera up seems to lessen the impact of it all. The game is perfectly playable but at this point feels kind of like trying to play a game you were really excited for on an under-powered PC. Still very much enjoyable but you can't help but feel the extra frames of animation you aren't seeing would be mighty nice.
I don't regret my purchase at all but I would have liked some more concessions to graphical fidelity in favor of framerate.