Medium sized village causes extreme lag

Whether I run this world on a server or locally, it causes extreme lag when any player is near the village. (Each tick takes several seconds, several are over 120 seconds)

Killing even a couple villagers seems to instantly solve the problem. I'm not sure if it's a specific villager, because spawning more doesn't seem to cause trouble (or at least not right away).

A copy of an affected world can be found here: (The village is just north of spawn)
https://www.dropbox.com/s/kg8wdp257znl6o4/Laggy%20World.zip?dl=0

This world has a small handful of command blocks running very simple commands on repeat, but disabling them yields no results.