I have recently upgraded my 8GB MacBook Pro (mid 2010, model ID: MacBookPro6,2) from OS X 10.6.8 to 10.11.4.

Under Snow Leopard, after I closed the lid it would take something like 30 seconds to write memory contents to disk before the HDD would spin down and the sleep light begin to pulsate.

Under El Capitan, it takes five to six minutes between when I initiate sleep and when the machine actually powers down and the sleep light begins to pulsate.

  • During this time there is very high CPU usage, as evidence by:
    • The fans often spin up (to very high speed, if I have closed the lid and zipped the machine into the neoprene case I normally carry it in).
    • The period of high CPU usage is clearly visible in Activity Monitor upon waking:

Screenshot after waking from full sleep; note CPU usage was very high, then moderately high while going to sleep; there is a momentary spike (presumably upon wake) and then drops to near idle again: full-sleep

Sreenshot after putting machine back to sleep, then waking again after one minute (while machine was still busy); note CPU was near idle until sleep initiated, whereupon it was very, very high, then very high, then back to near idle upon wake: interrupted-sleep

  • I note that /private/var/vm/sleepimage is exactly 4GiB, even though I have 8GiB of RAM. It was previously 8GiB under Snow Leopard.

Question: Is this behaviour normal? If not, what can I do to fix it? If it is, is there anything that can be done to mitigate it?

  • I would ensure you have adequate disk space. Anything below 10% of the total size of your HD will cause these types of slowdowns when it needs to write large amounts of data.
    – Pixelwiz
    Commented May 19, 2016 at 18:30
  • @Pixelwiz: You may well be right. But why? I understand SSDs can sometimes be slow when full, but my machine has an HDD - and this was never a problem under Snow Leopard.
    – cpcallen
    Commented May 22, 2016 at 9:41
  • Definitely not normal. I would try deleting Chrome, restart and see if it does it again. If you also have Firefox installed delete that. Test. Reinstall, Chrome. Test, reinstall Firefox test. I have had issues with runaway processes with Chrome and Firefox - hence my suggestion.
    – Deesbek
    Commented May 28, 2016 at 6:15

2 Answers 2


Is it normal? No. Not with an optimal install, optimal hardware & configuration. Is your computer stock or have you installed non-oem parts? Age can also be a factor as the thermal grease can deteriorate over time especially when a cpu gets overheated. Also Apple had indicated that you need a minimum of 1GB free to even be able to run effectively. My experience is that having much more than 1GB allows the system to run best.

What can you do to fix it? Take a free disk and install the OS on it. Boot from that disk and see if the problem disappears. If it is gone then it's a software issue. If it still exists, you have a hardware or resource issue. If it's software you can create a new user and log in under that account. If the problem is gone then it's the old user account. If it's not, do a clean install of the system. If the problem is gone then it was a problem with the system.

What can you do to mitigate it? See the second response to fix it or replace the machine.


Would just add - I had a similar problem with sleep on a MacPro 1.1 Tower. Turned out it was heat... which might explain why your fans are going up also. The Mac wont go to sleep above a certain temperature so will continue to run until this comes down which could be 60 seconds or 10 minutes.

I installed SMC Fan Control, a free app which allows you to take control of your internal fans and (typically) set them 25% higher. There is a free Temperature Monitor app that reads presents all the sensor values across your Mac. Sure enough, Ram and CPU were running 90+ degree under load (I'd installed additional server grade Ram previously. Whilst this wont kill them, its too high for sleep.

SMC sorted the temperature and the Mac sleeps in seconds now.

  • I sincerely hope this is not the case for laptops: not sleeping when too hot is deadly when the machine has the lid closed and is put inside a well-insulated slipcase. Under 10.6.8 sleeping was normally very quick, but once due to a glitch it failed to sleep entirely. When I pulled it out 45 minutes later it was almost too hot to touch and had developed hardware crash issues requiring main logic board replacement.
    – cpcallen
    Commented Sep 5, 2016 at 21:53
  • Hi - not sure about Mac laptops as a rule. On the tower I was pointed to the heat issue as a root cause and it turned out to be correct (I had already done a clean install and gone through my normal fault finding routine including hardware). Bringing the temperature down cured the problem for me on the first (post) sleep. IT also shut down much quicker. I have a MacBookPro 17" Quad i7 that I am using as a workstation right now working at a client's office Commented Sep 7, 2016 at 11:15
  • With the power plugged in it uses the full chips and the 1 GB graphics card into a 27' monitor. Multiple Adobe apps running, Office 360 (Outlook open all the time) etc and I have had no heat or sleep issues - it's on a desk well ventilated rather than my knees. Its running 10.8. Only issue I have had is Firefox and Chrome hogging the processor when temp and fans typical go from 47 degrees / 2800 RPM to 70 / 5500 RPM. I have cured this by ditching Chrome (Google run annoying crap in the background) and adding Flash and Ad Blockers to Firefox. Commented Sep 7, 2016 at 11:33
  • Would just add that I optimise the OS install (especially on laptops) - I use a font manager for example (Linotype) so the 300+ Apple/Microsoft/Adobe font sets are OFF even though they are placed by default in the system folder. Ditto removal of anything I dont need (printer drivers, language kits, etc). Dashboard, Launchpad etc are OFF as are fancy UI graphics like the Dock animations. I have found this makes a significant difference to boot, app launch and general processor / heat issues. Commented Sep 7, 2016 at 11:33

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .