[jashmatthews]

This may be true of Twitch but not GitHub. GitHub uses https://github.com/libgit2/rugged to bridge between Ruby and Git. As far as I'm aware, they still use Ruby to pull the diffs etc out of Git etc.

https://githubengineering.com/how-we-made-diff-pages-3x-fast... indicates they were still doing this as late as 2016.