Oops I did it again.
Dammit. The megagrinder is working wonderfully. Too wonderfully. The rate of mob spawning is off the chain, and all items are getting where they need to go. Carefully. In masterfully designed channels. Which endermen hate.
So when the endermen take out a block at the bottom of a channel, it makes a waterfall that cascades down. When this happens, the mob drop channels get stuck and the mobs don't die. Thousands of them. Causing unfixable lag.
That's happening on every floor, in all of the 9 holes. By my count, there's roughly 1600 mobs stuck in the grinder right now. I will continue to use creative mode to repair it...until endermen are nerfed per notch's design. SORRY!