It's well known that the Physics in this game are broken and have to be lowered to at least low even on high end spec to avoid stutter. Many with lower spec turn it off completely. It's also well known the in game Vsync caps FPS to 30, which can also cause lag.
What is less known is that triple buffering can smooth out gameplay quite a bit, and that it can be mimicked via simple methods like the one I exampled above. However you can also use Direct3DOverrider to force triple buffering, which also emits a tone when you launch the game so you know it's running.
If you get too much screen tear with Vsync off, you can enable it in your GPU control panel instead. Some games will not allow that though. In that case you can force vsync via...