[maicro]

I had a similar comment so I'll just add-on here - jitter definitely is a huge issue. If an interface is _consistently_ slow you know to slow down, space out actions and wait for visual confirmations; if an interface is generally responsive, though, you can get into a "rhythm" of actions which, which can lead to chaos and confusion as you try to figure out both the new state of the system, and what actions you need to take to get back on track.

[QuercusMax]

This is exactly what triggered the Therac-25 radiation therapy defect: the UI was very slow to update, but experienced users knew what order to hit the buttons to go through the screens quickly.

Except that there was a bug where if you go too quickly, some of the software safety interlocks didn't work right, and they had removed the hardware safeties in the update from Therac-20.