Have you looked into Scalar? It's built into MSFT git and designed to deal with repos that are much larger internally.
microsoft/git is focused on addressing these performance woes and making the monorepo developer experience first-class. The Scalar CLI packages all of these recommendations into a simple set of commands.
scalar and msft git (whose many features made it into mainline by now) addresses mostly things like improving local speed by enabling filesystem caching etc.
It doesn't address the issue of "how to clone entire 10GB with full history faster". (Although it facilitates sparse checkouts, which can be beneficial for "multi-repos" where it makes sense to only clone a part of repo, like in old good svn.)
https://github.com/microsoft/git