It still ran slowly on my machine. Typed characters were noticeable more sluggish to appear on screen. Just a bit, but noticeable and it was too much. Maybe it didn't work for some reason.
I used that for quite a while before I discovered Modific (https://github.com/gornostal/Modific). Similar functionality, except you can hit a shortcut and see what was on that line before the change - pretty useful stuff!
https://github.com/jisaacks/GitGutter http://www.jisaacks.com/gitgutter