Improve performance for long buffers

[jason-o-matic]

Occasionally I'll go to make a git commit with a large diff. Atom opens a new window, but unfortunately the window hangs and Atom prompts me to close the window after maybe 10 seconds. I disabled wraptor just to make sure it was causing the issue and the window loads just fine with it disabled. My buffer was ~700 lines in this case.

In my particular case of a large commit it would also be fine if wraptor just didn't process the diff portion, but it seems like we should be able to make it performant.