Is your Magic Mouse acting sluggish and tracking slowly? If so, there are several steps you can take to get it back up to speed (literally).
The first, easiest, and most effective thing thing to do is simply wipe clean the glass on the bottom of the mouse that houses the laser. Heck, I pick my mouse up and simply blow any dust off the glass when it seems “tired.” That almost always does the trick. If that doesn’t work, try one of these steps:
Download and install the latest Magic Mouse firmware. You can find out how to do so here: https://support.apple.com/en-us/HT201541 .
Reset the connection and re-pair the device. Go to the Bluetooth and Mouse system preferences and remove the mouse from your system. Turn the mouse off and back on so it goes into discovery mode and pair it back up with your Mac through the "Mouse" system preferences.
Reset the computer's PRAM by holding down the options-command-P-R keys at boot-up, letting the system reset a couple of times with these keys held before releasing them and allowing the system to boot normally.