A vanilla Minecraft installation on my Macbook Pro will regularly take my CPU to 100% and keep it there even after quitting. I don't think I'm doing anything particulary demanding with my setting, and in any case, it really does seem as if it's a bug if the game won't quit cleanly.

I'd certainly appreciate any advice on steps I might take to workaround this. I will try a completely clean reinstall just in case previous experiments with resource packs have caused a problem.

Further Information/Update: The problem recurs with a new install, but does not happen on a different map. The safe map is much smaller (a flat world that I use in creative to do redstone experiments); the unsafe map is pretty large I suppose, though hardly enormous and it used to work fine. Is there any possibility of corruption in map data leading to this buggy behviour?

  • Chunk corruption could be an issue, but this sounds like it may also apply to your Java installation. Try disabling any mods you may have, and try spawning a new map to check if it also lags on that one.
    – Timtech
    Commented Oct 7, 2013 at 21:41
  • It definitely seems to be an issue with the map; I copied it across to a different machine and the problem persisted. After updating Java, I also suddenly found the corridor I was in full of creepers and skeletons; the lag spiked seriously (1fps), presumably because the game was trying to simulate all of these new mobs. I think I'll have to go back to a backup of that world. Commented Oct 9, 2013 at 0:57
  • It definitely sounds like chunk corruption.
    – Timtech
    Commented Oct 9, 2013 at 10:34
  • I'm happy to go to the backup, but what's the recommended technology for dealing with chunk corruption? Commented Oct 10, 2013 at 13:03
  • I'm not sure exactly, I've never had a corrupted chunk problem.
    – Timtech
    Commented Oct 10, 2013 at 20:27

1 Answer 1


This is probably a case of chunk corruption. There is way away to fix the chunk, but BE WARNED!! This shall delete your builds.

  1. Go into MCEdit (IF you don't have MCEdit, download it and open your world)
  2. Select said chunk
  3. Delete it.
  4. Restart your game.

If you just want to get rid of mobs, you can select a chunk within MCEdit and there is a "delete mobs" button somewhere or "delete entities," something among those lines.

  • Thanks for the suggestion of MCEdit. I've long since restored from backup, and not had the problem recur, so I don't need it now, but I suppose I may need it in the future. Commented Jul 3, 2014 at 23:58

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