Choppy mouse on macOS Sierra 10.12.3? (Both trackpad and wired)
Cursor became so jumpy on El Capitan, machine unusable despite all manner of resets ... but cured for good, still cured in Sierra, by third internet reinstall from Recovery partition!

The third time I ran with no hope, but what the hell it's easy enough, and ....no more trackpad or mouse cursor craziness!

If you really want to do it right, back up or make a clone, &amp; erase disk with Disk Utility in Recovery Mode for a complete, clean install.