Well, I tried several times, and it did crash a couple of times, but it would also play fine for long periods of time as well. I tried it both in Firefox and Chrome. It seemed to run better in Chrome...
I ran it in debugger mode several times too, and most of the work is being done TransformWorldXYZ. I thought maybe it was getting stuck in an infinite loop or something like that. But I don't see any problems there.
On my system it would occasionally stop for a few seconds, but then keep going. I thought that might be cause by garbage collection, but there is very little creating and destroying of objects.
So, I didn't see any obvious problems...