Note

On macOS you can speed up the key repetition even further than the settings (System Preferences -> Keyboard) allow by setting these values in your console (or adding them to your nix config as I did):

defaults write -g InitialKeyRepeat -float 10.0 # normal minimum is 15 (225 ms)
defaults write -g KeyRepeat -float 1.0 # normal minimum is 2 (30 ms)

I found this on StackExchange.