The closest competition to GitHub seems to be GitLab at the moment, but I heard it's slow to some users. The UI also felt a bit "off" to me (primarily because I'm used to having code, not the README, as the index page of a repo)
I have my private projects on GitLab because it's free. (BitBucket before that; good riddance)
I definitely wouldn't say gitlab is slow in the empirical sense, but browsing repos is definitely a bit more sluggish than github. Maybe it's just more noticeable since it's an SPA.
I say that as a someone who uses gitlab for all of my personal projects.
My university uses gitlab and it feels very slow. Pushing changes takes 5-10x longer than anywhere else, even from the university network. (compared to github or even my server sitting at home on a normal home DSL connection)
I have my private projects on GitLab because it's free. (BitBucket before that; good riddance)