Keyboard latency
I'm surprised the "humans don't notice 100 ms" argument is even made.  That's trivially debunkable with a simple blind A/B test at the command line using `sleep 0.1` with and without `sleep` aliased to `true`.  To my eyes, the delay is obvious at 100 ms, noticeable at 50 ms, barely perceptible at 20 ms, and unnoticeable at 10 ms.Not to mention that 100 ms is musically a 16th note at 150 bpm.  Being off by a 16th note even at that speed is – especially for percussive instruments – obvious.On the other hand, if you told me to strike a key less than 100 ms after some visual stimuli, I'm sure I couldn't do it – that's what "reaction time" is.