If you are using ST3 you can use non blocking mode and GitGutter will run in a seperate thread.

EDIT: Here is the section on the read me about it: https://github.com/jisaacks/GitGutter#non-blocking-mode

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.

Aha! I didn't know about this. You're awesome!

Really?

I've done this with "big" files, as well as large folders and it works perfectly both locally and over a NFS share.

How many LoC are the files you editing?