if anyones interested follow this tutorial
basically the codes allow ur computer to sink its fps with the physics. i can usually render these in wide range of fps, depending on the number of collisions between objects. can be as low as 8fps down to about 2spf.
rendering more objects also takes a bit of extra hardware.
for more objects to be able to display before overloading the screen u need a lot of vram (Ex. 512mb may equal around 5000 crates... 1024mb might be 10,000 crates... etc)
you can also render longer scenes depending on the amount of ram u have. I'm using 4gbs and allows me to render a scene longer.