Projects::TreeController#show is slow because of multiple things

It looks like the p99 for SQL has spikes to 4 seconds, git has spikes to 15 seconds. It also looks like the mean of SQL queries executed is at 30.

Check live metrics here

I think that this controller can be optimized both from the git and the database perspective.

From the git perspective it looks like the main WALL Clock timings come from Rugged::TagCollection#each_tag

cc/ @andrewn