Git in the bash terminal in Windows 7 seems to slow down to a crawl once you start fiddling with your bash prompt and whatnot. I finally got sick of it and found out that adding this sorts it out:

$ git config --global core.preloadindex true
$ git config --global core.fscache true
$ git config --global gc.auto 256

 

Blatantly plagiarized from StackOverFlow.