vc-git-state very slow, waiting for `git diff-index`, in large repositories

[Matt McClure]

Emacs opens files from one of my largest Git repositories very slowly. It looks like it spends most of that time waiting for `git diff-index -z HEAD -- <file>`.

I upgraded this morning to http://emacsformacosx.com/emacs-builds/Emacs-2012-07-28-109240-universal-10.6.8.dmg hoping that it would include the fix for http://debbugs.gnu.org/cgi/bugreport.cgi?bug=11757 and that that would make Emacs fast enough. But it was still very slow.

I see there's another open ticket citing the call to `git diff-index` from `vc-git-state`: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=8288

Applying the workaround from comment 14 in that ticket works for me, but it seems like it would be better to address the problem closer to the root in the Emacs source and/or in Git.

What would you recommend?

--
Matt McClure
http://www.matthewlmcclure.com
http://www.mapmyfitness.com/profile/matthewlmcclure