Retina Macbook pro suddenly extremely sluggish

Discussion in 'MacBook Pro' started by inscrewtable, Jan 3, 2014.

  1. inscrewtable macrumors 68000


    Oct 9, 2010
    Just today my rMBP mid 2013 model is suddenly running as if it only has 500mb of RAM, finders are taking 10 seconds to open dragging windows is jerky and even safari is impossible.

    I have restarted a few time with no difference in performance. At the moment only activity monitor is open and Safari and the kernel task is showing 600% CPU usage which I don't understand at all.

    The only thing I can think of is that it is very hot today, currently in the room where the rMBP is operating its 40ºC and the fans are running at about 5000 rpm. However if I check the operating temperatures they are normal, GPU 50ºC CPU 45ºC max temperature of anything is only 52ºC so no problem there.

    The only thing that is puzzling is this ridiculous kernal_task CPU usage.

    Any clues?
  2. mitasol macrumors newbie

    Dec 6, 2013
    sounds strange, just a quick question - do you have headphones connected?
  3. jps24 macrumors member

    Jul 16, 2012
    I would try a couple things. I would reinstall the OS and see if it still does it. If you do not want to lose the info on it I would install the OS on a flash drive and boot to that and see if it still does the same thing.
  4. inscrewtable thread starter macrumors 68000


    Oct 9, 2010
    Update, it would appear that indeed it is simply the external temperature that is causing this. Bottom line, rMBP will not operate properly in 42 C ambient temperature, and to be fair Apple lists 35 C as a maximum operating temp.

    This is curious because even at 42 C ambient temperature, it did not affect the operating temp at all which was the same as if the ambient temp was 30 C.

    It looks like it will work ok at 38 but after that, it's anybody's guess.
  5. maflynn Moderator


    Staff Member

    May 3, 2009
    I don't think it was the ambient temperature as much as the internal temperature. When the CPU gets too hot, it throttles down. I'd suggest getting a utility like iStat menus to report the internal temps of the MBP.

    While the ambient temperature will have an impact on the internal temps overall, its how much heat the laptop is generating and its inability to shed it, which is causing the CPU to throttle.

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