Nether lags since upgrading to snapshot.

When playing on a server some of the members have 1-2 mins of lag when interacting with blocks/chests and others are fine. Packets are not being lost during a ping test. The players location in relation to the server doesn't seem to have any impact. FPS is >40. Running in 1.7.4 on the same server there are no issues. Attached is a forced crash report