Hi all,
tl;dr: I've cleaned up the mediawiki/core repo, and performance for fetch/clone operations should be noticeably faster.
So, due to some recent upgrades in Gerrit, we've now got GC support in JGit as a result. Gerrit supports this functionality, which will greatly reduce the size of our repositories on-disk. It also makes use of an improved bitmap algorithm for fetches & clones, making them wayyy faster. I've now run this on mediawiki/ core, and the repo went from 3.0G down to ~620M on disk. You should now notice all read actions (over https & ssh) to be way faster--a fresh clone should now only be limited by your bandwidth, not how fast Gerrit can serve the repo from disk.
If you notice *any* problems with mediawiki/core, please let me know immediately. If everything looks good, we'll set this up as a cron to run weekly or something for all repositories.
-Chad