LOL. In 2007, I did a side-by-side comparison of SVN, Mercurial and git with my codebase at work (~700k LOC). I know hg got faster eventually, but I still can't believe people say "hg should have won the DVCS war" with a straight face. It was orders of magnitude slower in my tests. Like, 20 minutes to commit large xml files (yeah, I know, but that's where we were). Not just a few ms slower, unbearably slow for several things.

I liked its features better, but chose git, and that was the correct decision.