prevent frame down in mass rigidbody collision

in situation like figure, a game’s frames are slow down to under 10.

how can i prevent this frame-dropping?

each cars have a rigidbody and capsule collider.

and Rigidbody.velocity moves a car.

Just because it happens when you collide doesn’t mean it’s the collision, use the cpu profiler to find what is taking up the cpu, once you do, try this.