I use 60Hz keyboard autorepeat for navigation, so latency is very noticeable. I need prompt visual feedback to tell me if my estimate of the autorepeat startup delay is too short or too long. The quicker I get it the shorter the navigation sequence I can make while still having a good chance of hitting the correct frame-perfect key-release timing. Note that reaction time is irrelevant; I anticipate everything and only use the visual feedback for timing adjustment ("rushing or dragging" in drumming terminology).