Faster than 20 crossings per second (but not much)

Re: the doorway conversation where we agreed that 20 shell crossings per second seemed awfully few, I made the following plot. It demonstrates that there are more like 150 or so for 101 particles (which was the number I used for the timing studies). I ran this on Jupiter and was careful that nobody else was using memory or CPU at the time. For 301 particles, there are around 50 crossings per second, which to me still seems slow.