Quoting from Twitter: "For 1.11 there is a new game rule called "maxEntityCramming" with the default set to 24 (i.e. 25+ entities at the same spot will suffocate)

Since this affects grinders, chicken machines, elytra launchers, and so on, it will be included in the next snapshot"

Basically, if a bunch of mobs get stuck in a small area (like, say, the drop point of a grinder), they'll start suffocating and die. The era of laggy grinders with 100+ entities might be coming to an end, finally...

Except they're not the ones usually placing stress on the server due to mob farms...

That's a funny way to spell 7 :U