There are things worse than that, even. And those things invalidate discussion of american school shootings as much as the shootings should invalidate this discussion.
it often means having to run the game twice on the same machine.
Not quite that much. A sane game would run all players in the same simulation, assuming they're in the same map. Multiple cameras would increase the amount of stuff drawn on screen, but at least the amount of pixels to calculate stays same, which helps a lot.
Try the toothpick or something stronger than a brush anyway. I have used a toothpick and a sewing needle to dig the compacted lint out.