when loading chunks with villagers and iron golems in them, the entities appear somewhere abnormal, often on roofs, in the ocean or inaccessible areas. I have on occasions seen these entities quickly speeding, without moving, as if teleporting to these areas. It may be linked to the bug whereby iron golems spawn often, as the iron golems end up else where or in oceans just to sink and do not despawn or die, therefore lagging the game and making the villagers spawn more iron golems to replace the absence of the others.