If, like me, you're someone who likes to have your mouse on maniac speed settings, but doesn't like the slow speed that MacOS gives you even with the fastest setting.
1. Do it by the command line via terminal (which involves restarting your machine each time you set it). Using something like this:
defaults write -g com.apple.mouse.scaling 5.0
2. Download this nice little tool, which changes the setting instantly: