AutoSim.cs

using UnityEngine;

public class AutoSim : MonoBehaviour {

    [SerializeField][Range(0.1f, 1.5f)] float speed = 0.1f;

    private void Awake()
    {
        Physics.autoSimulation = false;
    }
    private void OnDestroy()
    {
        Physics.autoSimulation = true;
    }
    void FixedUpdate () {
        Physics.Simulate(Time.fixedDeltaTime * speed);
	}
}