Comment by suby

I don't actually know, but I'd wager a lot that it's the graphics rather than the physics which causes the game to be slow. Generally the expensive thing in video games is rendering. Computing the next world state is generally relatively cheap, especially if we're talking about a confined area with a very small number of rigid bodies (the ball, flippers, bumpers). A pinball game like Pinball FX that's rendering a 3d world with lighting, it'd just be shocking to me if the physics were to blame for the performance.