Beauty!

I'd love it more if there were a "kinda figure out the normal pace of output and change color when it varies by %" mode. This would make it a time derivative color changer, perhaps. Use case: are we in the lunch rush yet, or just poking along at our usual lazy morning pace. It could also mark out delays in expected periodic output that sometimes misses a beat (showing a bug in real time software that isn't, quite)

Thanks for the feedback, I like this idea. I can imagine it working well in 256-colour mode, gradually increasing colour intensity in line with write-frequency.