yachi

make sure "brew --prefix git" does not appear in ~/.gitconfig, or ruby will be fired up every time you call git diff

with brew --prefix git in ~/.gitconfig

$   time git diff
git diff  0.20s user 0.07s system 94% cpu 0.285 total

with absolute path in ~/.gitconfig

$ time git diff
git diff  0.05s user 0.04s system 92% cpu 0.095 total

good tip! didn't know the -i option, always wondering how to do that with sed