Wikis: Optimize empty? check
From https://gitlab.com/gitlab-org/gitlab-ce/issues/40101#note_87760258, it looks like 5% of one Wiki repository is due to the fact that we have to render one Wiki page just to tell if it's empty:
We could simplify this a lot more by just checking if there are any files. This will likely require a Gitaly endpoint.
/cc: @jramsay