Chunks appear to not load, relogging fixes this, though. Also, weird lines appear when loading new chunks.
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Confirmed for 14w25a
It seems that it is very bugged because like you can see in my screenshot it sometimes has 0 chunk updates and 2 seconds later 212
Maybe it is also a rendering bug because it seems to have already loaded the hitboxes and mobs

Is MC-56897 your issue?