You got Reflecting, lightning and shadows when you "run" a level. Try turning them all off !
My computer will rull pfx2 fine until I see water. Which means I can't play any levels at all. If I make a new level, everything runs perfectly smooth. As soon as I see water, the framerates drop to like 1/2 FPS.
Is there a way to turn off the fancy, textured, reflective water? I can't seem to find an options menu anywhere... Am I just blind?