In the current version, when villagers pathfind to their job blocks, it causes the world to lag (not FPS lag, but all entities move in slow motion). Having around 15-20 villagers in one area pathfinding at once is enough to cause a lot of lag even on a good pc that has no performance issues. I don't know if this is realted to anything else with villagers but to me it seems to happen when they pathfind or look for their job blocks, other times its fine.