Projects API is better... but still slow :)

Requesting the URL /api/v4/projects?per_page=100 takes 5 seconds to load, given an instance with 100+ projects.

This isn't nearly as bad as previous results (some of the worst issues with N+1 queries were addressed in gitlab-ce!12679), but as the previous ticket (gitlab-ce#33748) points out, it's still nowhere near as performant as an equivalent request on Github (<500ms), and certainly could be improved, making the endpoint significantly more usable.

Gitlab Version: 9.5.2