After doing that this is what I am seeing within moments after issuing phd start and our idle slowly trickles to 0%. User 501 is our Phabricator user (daemon-user).

Here is a quick shot of what appears in top.

I still see a very large number of Mercurial processes. However, it seems to have helped with load. Is there a way to limit the number of hg processes that get run for this?

@epriestley: Enormous is relative, but yeah I'd say it has an abnormal amount of branches.

We are experiencing this exact same issue after upgrading our Phabricator to the latest version last week.