Sometimes when I am playing the Direwolf20 modpack I start getting sever lag spikes. Whenever I check the console this is the error that is displayed (in red)
2013-03-19 16:30:59 [SEVERE] [ForgeModLoader] Detected leaking worlds in memory. There are 5 worlds that appear to be persisting. A mod is likely caching the world incorrectly
2013-03-19 16:30:59 [SEVERE] [ForgeModLoader] The world 6ad77853 (New World) has leaked.
2013-03-19 16:30:59 [SEVERE] [ForgeModLoader] Detected leaking worlds in memory. There are 5 worlds that appear to be persisting. A mod is likely caching the world incorrectly
2013-03-19 16:30:59 [SEVERE] [ForgeModLoader] The world 6ad77853 (New World) has leaked.