Tressure chest GUI on ship recks not displaying.

When trying to open chests on ship recks, the GUI is empty; and any further attempt to access the GUI fails, with the chest not responding to the player. If the chest is broken it takes from thirty seconds to 2 minuets to spawn the correct drops (Incressing in time taken to spawn the items every time you open a new chest); and possibly crashing the game.
Update: Found this in the game output: [00:04:15] [Server thread/WARN]: Can't keep up! Is the server overloaded? Running 2162ms or 43 ticks behind.