Try Physics. Disable cubes collisions with other cubes, they should only collide with the immovable ground.
Or you can use Bullet behavior with gravity and Bounce off solids=yes. On Collision with the ground reduce bullet speed. It will not look that nice, but should have better performance.
Oh, k, thanks, but, sorry for asking more again, but, you could make your own version? Like, everything i made is not that 70%, so, your code should be better in perfomance than me, or just in another way, for me to see will be better, and thanks again for helping me!