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. Akos

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

  2. hoshang

    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

  3. text based rpg

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

  4. leke

    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

  5. hansthorp

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

  6. meet

    can’t delete, required in os x

  7. Andri Baghaskara

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

  8. Vicente Machado

    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.

  9. joe

    doesn’t seem to work in osx el cap

  10. Prosenjit Ranjan Nath

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

  11. Prosenjit Ranjan Nath

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

  12. Ahmed Mujtaba

    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 !

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