So, I was thinking, if you have a quite laggy PC(including Me), and want more fps, the devs should add a feature that enables you to set a distance for other car's physics to deactivate to improve fps if the physics is still on when you say, 1000m away and you can still see the car, say wobbling. I know what your thinking, what if your in free camera and you want a cinematic scene of a your car driving off a cliff, or you make the camera go too far away the car would just freeze on the spot, sitting there. The physics would never disable for your car no matter what the circumstances.
One of the planned features is jbeam sleeping. It's basically what you described, in that once an object reaches a negligible speed and/or a certain distance from the active player vehicle, its physics deactivate. This is commonly seen in most games/game engines with rigid body objects. That said, this feature is mostly meant to be for non-vehicle soft bodies in the level (stop signs, traffic cones, concrete barriers), not so much for running vehicles. It could still be useful, but you'd need to find a way to simulate at least the bare bones minimum to allow distant vehicles to continue driving in, say, races and car chases. Lastly, if you're having trouble running the game, bear in mind that the elusive-but-inevitable Race Update is to include slight performance boosts.
