Multiplayer minecraft used to work excellent, but recently (1.9 pre-4)
I and other people on the server has experienced lag issues. Mobs are moving really slow in what seems like 2 frames per second, and blocklag is making the game almost unplayable. Everything else seems fine. Players are (mostly) moving fluently, but mobs and blocklag is terrible. Also furnaces are slow.

Steps to Reproduce:
1. Play on a multiplayer server in minecraft 1.9 prerelease 4