Yea its my fault, i left a spawner on and the mobs werent getting killed.i removed the floor underneath them but that only aggravated the issue. there's tens of thousands of goblins falling into the void now. coords are under the map. Dimension = Last Millennium. VERY SORRY!
well my part of the cause is fixed. but its still lagging somewhat. but im not sure what the other part of the cause is.