This was bound to happen. I coded up a super basic n-body simulation in Processing. It works by just iteratively adding terms to the equations of motion for each particle. Below is a .gif for 7 (7!) particles. The central one is more massive than the others, but there is (at least in principle) still interaction between the other particles. Notice how slow it goes! That means my computer is really taking some time to crunch those numbers! There's probably a good reason why we don't use this naive method for real N-body simulations.