1. Open a Terminal Window.
You can Spotlight for "terminal"
2. Check your mouse speed.
Enter the following command to see what your current setting is:
defaults read -g com.apple.mouse.scaling
This will return a numeric value, the speed of your mouse.
3. Set your mouse speed
To speed up (or slow down) your mouse tracking, you can simply change this number accordingly by typing the following command, replacing the “your_mouse_speed” with a new number such as 5.0. Notice that read has been changed to write:
defaults write -g com.apple.mouse.scaling your_mouse_speed
The maximum mouse speed on mac desktops is 3.0 (when maxed out in system preferences). I use 5.0 and it works well for me.
defaults write -g com.apple.mouse.scaling 5.0
You may need to restart your mac to see the changes take effect.
Hope that helps.