git-fetch per-repository speed issues

Ok, so maybe X.org is using git in an unexpected (or even wrong) fashion. Our environment has split development across dozens of separate repositories which match ABI interfaces. With CVS, we were able to keep this all in one giant CVS repository with separate modules, but git doesn't have that notion (which is mostly good). As such, we could use cvsup or rsync to update the entire collection of modules.

With git, we'd prefer to use the git protocol instead of rsync for the usual pack-related reasons, but that is limited to a single repository at a time. And, it's painfully slow, even when the repository is up to date:

$ cd lib/libXrandr $ time git-fetch origin ...

real 0m17.035s user 0m2.584s sys 0m0.576s

This is a repository with 24 files and perhaps 50 revisions. Given X.org's 307 git repositories, I'll clearly need to find a faster way than running git-fetch on every one.

One thing I noticed was that the git+ssh syntax found in remotes files doesn't do what I thought it did -- I assumed this would use 'git' for fetch and 'ssh' for push, when in fact it just uses ssh for everything. This slows down the connection process by several seconds.