MacBook Pro Running Slow On Battery – Fix It!

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Have you started to notice that your MacBook Pro has begun to run slow, only while running on batteries? The following fixes should help you fix MacBook Pro running slow on battery problems once and for all.

First of all, before you get to the fixes, you want to make sure that your MacBook’s performance problems are indeed occurring only when it is running on batteries and not when connected to the MagSafe connector.

To confirm this, please carry out the following steps;

  • Plug in your MagSafe
  • Power up your MacBook Pro
  • Go to Activity Monitor -> CPU -> CPU Usage Graph -> Note down CPU activity %
  • Unplug the MagSafe connector
  • Go to Activity Monitor -> CPU -> CPU Usage Graph -> Note down CPU activity %

Check to see if there is a significant difference between the two CPU activity % figures. When connected to your battery, your CPU activity % will show as 60%+. When connected to MagSafe, this figure will drop down to less than 10%.

Now that you have confirmed that your MacBook Pro is slow only while running on battery, let’s proceed to the potential fixes.

1. Deleting a certain .plist file

You will be shown how to find and delete a certain .plist file on your MacBook Pro. First, please take a backup of this file before you delete it. If your Mac starts to act funny after carrying out the following procedure (shouldn’t happen though), please restore that file to its original location.

Identifying your Mac’s model

  • Click on Apple Icon in Menu Bar
  • Click on About this Mac
  • Click on “More info”
  • Click on Hardware (found on the left side)
  • Write down the displayed Model Identifier e.g. MacBookPro x.x

Finding and deleting the problematic .plist file

  • Open Finder
  • Select Macintosh HD (The one with OS X installed on it)
  • Select System -> Library -> Extensions
  • Find and Locate a text file called “IOPlatformPluginFamily.kext”
  • Right click on the file and select “Show Package Contents”
  • Click Contents -> Resources -> Plugins
  • Right click on ACPI_SMC_PlatformPlugin.kext
  • Right click on it and Show Package Contents
  • Click Contents -> Resources
  • Find the .plist file that you identified earlier (e.g. MacBook pro x.x)
  • Delete the file
  • Restart your Mac
  • Hopefully, this would have fixed your Mac running slow on battery problem!

What does deleting the above .plist file actually do?

The theory is that the .plist file identified above is the file responsible for telling your Mac to slow down, when on battery power, so your battery life can be extended. More technically, the file actually instructs your Mac’s processor to work at a much slower clock speed than it is usually capable of, thereby resulting in dramatically reduced performance levels.

In some cases, instead of just some minor slowdowns, this .plist file brings about a crawl, leading to performance issues that probably made you find your way here to this page.

Remember, deleting this .plist file is a hack discovered by users after several trial and error methods and not something that is recommended by Apple, at least not officially. However, several hundred users have vouched for this method in forums and various types of online discussions.

Check your MacBook’s Battery Health

Sometimes, it could just be that your MacBook’s battery has run out of juice, pun intended! Just because it shows a full charge icon doesn’t always mean that the battery is working like it is supposed to be working.

Run a quick diagnostic test on your MacBook’s battery. Here’s our post on how to monitor MacBook battery health.

If the tests show that your MacBook’s battery has deteriorated significantly, it makes sense to invest in new batteries that might just fix your Mac’s slow performance issues, while running on battery power.

Other ways to possibly fix this problem is to carry out a SMC reset, PRAM reset and maybe by running a Repair Disk Permissions process, all of which are explained in a post that is linked to at the beginning of the article.

If you have used any other method or have read about other potential ways to fix a MacBook’s performance woes while on battery power, please do share them with us and we will in turn be glad to share it with our readers!

About the Author
Michelle, author at Mach Machines. A tech lover and an insatiable latte drinker. Michelle blogs about improving the personal computing experience.
  1. Joerg Reply

    Anyone knows if it can be done in High Sierra 10.13.2??
    Same procedure as El Capitan ?
    Thank you!

    • Kylie Larson Reply

      Hi Joerg! In High Sierra: open Finder, hold Option, click on the Go menu, go to Library > Preferences. You can delete the plist file(s) there.

  2. david Reply

    My Mac was so slow after replacing the battery, after searching google for answers I found your website! deleting the .plist made my Mac super fast! Thanks

  3. Aubergiste Reply

    Hello thank you, your method improve greatly the performance. But it doesn’t completely fix the problem. The CPU seems to be running at the slowest frequency no matter the resource needed. For instance my MacBook Pro 2011 core i5 2.3 GHz runs only at 800 MHz on battery with this method.
    I monitor the cpu frequency with the istat application (+intel power gadget ).

  4. Julianne A Reply

    Please try this, installing the new battery. Charge it to 100%. Turn off your computer and leave it connected to the ac adapter for at least two hours after it reaches a 100% charge. Then let the battery drain, I turned off all of the energy saving aspects. Then I recharged it and it’s working great so far.

    I was having issues with my cursor overreacting after I installed
    the new battery. Plus my computer was slow and the spinning wheel of death was happening a lot.

    This totally fixed the issue! BTW my battery lasted almost 7 years, it’s a 2011 Macbook pro that has had issues with the video card more than I’d like to tell you about. It’s been worked on at least 5 times. APPLE should have replaced my computer! Never buy from best buy, I’ve learned my lesson!

  5. Scott Mason Reply

    I put in a replacement battery on my mid-2012 macbook pro 15 and when I restarted was crazy slow finally got it to load up.. and checked activity monitor but instead of low cpu it was maxed showing 700+% cup usage? doesn’t sound like the same problem ie the cpu being gated this is it on full tilt? Has anyone else seen this? will try removing battery to see if it will run with just plug. and then try getting a new battery?

    • Kylie Larson Reply

      Was your replacement battery from Apple?

  6. James Reply

    I can’t see my mac number on the folder of files to delete it

  7. James Shipwright Reply

    this file is not in the folder that is suggested and not on my mac at all. Can anyone tell me if there is a different file on 10.9.5? Would appreciate it, macbookpro runs brilliant without battery, put a new non apple battery in and it runs far too slow to even type a search in google

  8. PELAGIO Reply

    After disable SIP I was able to delete the file and restart my Macbook pro / Now my computer is working well on battery…

    Thanks for the Help!

  9. Juan Reply

    hey guys,
    i also tried the first method – deleting the plist file – and it has improved a lot. the mac was so slow the mouse was barely moving. now it is much better, but still a lot slower than being plugged in.
    do you have any ideas what the problem can be ?

    thanks!

  10. Keyur Reply

    I had a similar issue.I am using macOS Sierra 10.12.6.I tried Vicente Machado technique first then I deleted plist file successful.

    Thanks to Vicente Machado & Michelle. You saved my money 🙂

  11. Iwit Reply

    this step work for me..im using mac sierra,note if u’re using win elcap or higher, dont forget to disable sip for open access to modify/remove plist file..tks alott…

  12. Rajesh Reply

    Hi – Can some one advise what to do with Mac Air. Not able to find system folder itself

    • Kylie Larson Reply

      In Finder: Preferences->Sidebar: check Hard Disks under Devices. Then in Finder click your startupdisk in the sidebar, the System folder is visible in there called Library. Let me know how it goes!

  13. Steve Dutton Reply

    The .plist for my MBP 15″ Retina (11,4) is not found. Is it using a different .plist or is the .plist located in a different location?

  14. Steve Dutton Reply

    I came across this thread because I notice my 2015 MBP Retina slowed to a crawl when I was just using the battery. I followed the directions and got to the location of all the .plist files, but it looks as though the later Macs are not listed. My MBP identifier is 11,4 . . . there is no .plist file for that MBP. Any thoughts or suggestions?

  15. Ahmed Mujtaba Reply

    Thank you so much !!! You saved my macbook pro running mac os sierra . For everyone using el capitan or later should first disable SIP from the recovery partition and then try to delete the file ! Once again thank you so much !

  16. Prosenjit Ranjan Nath Reply

    Im using sierra and solved the problem following the instructions. Thanks a lot #Michelle Smith and #Vicente Machado.

  17. Prosenjit Ranjan Nath Reply

    Im using Sierra and facing the same problem. Its showing required in OS. Please help me.

  18. joe Reply

    doesn’t seem to work in osx el cap

  19. Vicente Machado Reply

    for everyone running el capitan, you need to disable SIP before deleting the file, to do so follow these steps -> https://www.macbartender.com/system-item-setup/

    You don’t need to install this app called bartender, just scroll down untill you find the intructions on how to disable SIP and enable back again (after you restart and delete the file). That’s what I did and it works.

  20. Andri Baghaskara Reply

    ergh. it can’t be done in the OS X El Capitan.

  21. meet Reply

    can’t delete, required in os x

  22. hansthorp Reply

    it’s there a way to solve this problem for a macbook on OS captain??
    thanks in advance

  23. leke Reply

    Hi,
    I tried deleting this file on my MBP2011, but it says“MacBookPro8_1.plist” can’t be modified or deleted because it’s required by OS X.
    I recently upgraded it to the el capitan, please help

  24. text based rpg Reply

    This is my fitst tіme ggo tо sеe аt hhere ɑnd i am
    in fact pleassant to rewad everthing at ɑlone place.

  25. hoshang Reply

    thanks so much for this article .. it really made the difference, but I dont understand as to how this problem developed after three years on my macbook pro .. however, its fine after this file deletion .. cheers

  26. Akos Reply

    Thanks a million. You just saved me the cost of a new battery!!!

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