Quoting KatolaZ (katolaz@???):

> The main limit of Gitlab is the fact that it depends on rails. And
> rails is not meant for scalability, IMHO.

Yes, that really is a serious limitation. The Wikipedia page about the
GitHub codebase mentions only that it's written in Ruby (and some bits
in Go), _but_ in truth it does appear to be a Rails app. (You seem to
speak from experience, which is deeply appreciated. By contrast, I'd
only heard the thing spoken of as a GitHub workalike.)