1.6 Zombie Hordes on Mac make game unplayable.

The game runs smoothly until nightfall. I was in an NPC village and the zombie hordes arrived, at which point, my system started lagging to the point where the game became unplayable. Block-lag was severe and entities moved in chunks.

Killing the zombies resulted in regular speeds and a return of playablility.

Switching to creative mode did not affect the lag.

Altering video settings also did not affect the lag.