http://www.reddit.com/r/programming/comments/1yts5n/facebook_open_sources_flint_a_c_linter_written_in/
Somewhere in that thread was a mention of facebook moving away from git because it was too slow. I thought it was interesting and found this info on the topic ... They rewrote some sections of Mercurial to make it scale better, and got it working faster than git in their environment. https://code.facebook.com/posts/218678814984400/scaling-mercurial-at-facebook/
