If you disable Vsync in the main menu (not in game !!!) then play as usual, the game will run a lot better : while before it was sometimes running at 40fps, now it's running 60fps every time, fully maxed, and definitely on par with Windows !
Dunno if it's a feature of Vsync, I guess maybe the game is running at 59fps, not exactly 60fps, and vsync blocks it at ~30fps... I don't have screen tearing either without vsync, so if you want a BIG fps boost (in my case almost 15fps boost in "complicated scenes) you should disable it.
EDIT : btw is there a way to force FSAA ? on WIndows you can force it via the nvidia panel, but forcing it via opengl profiler wont work
I'm not sure where you're reading fps readout from since Bioshock has no built-in way to display frames per second AFAIK... unless you're guesstimating? Correct me if I'm wrong, please.