Mercurial was optimized for performance on windows. On other OSes it was worse. But the reason it didn't win isn't that. It was GitHub. GitHub changed it from

Mercurial was optimized for performance on windows. On other OSes it was worse. But the reason it didn't win isn't that. It was GitHub. GitHub changed it from "use one of several analogous products"[0] to network effects. [0] Joel, founder of StackOverflow, had a GitHub like competitor that used either git or mercurial commands on the same repository. Just as one example of how similar they are.