5.3.0-Alpha-1  Date: 2013.05.23. 6:47:18

- New Loading routines, Carbonite no longer quietly during loading screen, but after when game is loaded. This causes a small delay once your ingame as everything initializes, but stops FPS drops if you login during combat. Will wait until you exit combat to load as well.

So we have to wait until the loading Carbonite or at least 5 seconds.
Perhaps it would be worthwhile to wait for the end of combat.