How do I speed up the simulation of a rigidbody?

Questions & Answers
1

I really doubt this is possible, but I’m just asking for confirmation.

In a scene where several rigidbodies are being simulated, is it possible to slow down the simulation speed of just one of them?

2

You can turn Use Gravity off and set the mass to a huge value - this will slow down reactions to collisions or applied forces. The gravity may be simulated with a few lines in FixedUpdate:

var myGravity = 4.8; // set the local gravity (regular gravity is 9.8)

function FixedUpdate(){
  var curVel = rigidbody.velocity;
  curVel.y -= myGravity * Time.deltaTime; // apply fake gravity
  rigidbody.velocity = curVel;
}

NOTE: This is physically correct - the rigidbody will suffer an acceleration similar to gravity, but with a different value. Like in real life, the acceleration doesn’t depend on the object mass.