The “Optimizing Your Mac” Notification in Mac OS X Explained

Jan 28, 2016 - 15 Comments

Optimizing Your Mac notification in Mac OS X

Some Mac users may see a notification alert pop-up from Mac OS X in the corner of their display with a message stating “Optimizing Your Mac – Performance and battery life may be affected until completed.” While there aren’t any additional details offered in the notification, there is a “Close” button, which will dismiss the alert. Typically this optimizing message appears after a system software update has installed, logging in to a new user account, or if the Mac has been rebooted after a long period of not being restarted. So, if you see this alert message, what’s going on and what should you do?

The answer is simple; do nothing, let the optimization process complete on the Mac.

The optimizing process can take a few minutes to a few hours, depending on a variety of things, including speed of the computer and drive, and what tasks are being performed. And yes, as the notification mentions, the Mac may be running slow as a result of the tasks going on behind the scenes in MacOS / Mac OS X.

Why You Might See “Optimizing Your Mac” Alerts

For those that are curious about what exactly is going on when this alert message comes up, the specific processes can vary as can the functions, but often you’ll find it’s one or more of the following:

  • The permissions repair process repair_packages
  • Spotlight related processes indexing the drive, including index agent, mds, mdworker, or related processes indexing a drive
  • iCloud Photo Library, photolibraryd, or Photos app completing a migration
  • Various other system level functions or processes, whether find, makewhatis, ac, kernel_task, amongst others

Each of these will be going in the background and you’re free to use the Mac as the task completes, but as the alert says some things may be a bit slow or battery life may be temporarily reduced as this occurs.

If you want specifics, the easiest way to see exactly what is going on during this “optimizing your Mac” process is by going into the Activity Monitor application and sorting by CPU or by Energy usage, as long as you show processes by all users and system, you should quickly be able to see what exactly is going on. But whatever you do, don’t quit the process that is in use, you do not want to halt the optimization process mid-task as it will either just run again from the beginning, or could potentially cause a problem with whatever it is attempting to do.

Remember, just let the optimization processes run and complete. If you have a Mac laptop then plug it in to a charger and let it finish, otherwise just let the Mac finish the work.

This alert dialog is visible in many modern versions of Mac OS X, though many users will never see it at all. The message seems to appear most often after updating system software to a new point release, or going to an entirely new release version (say from Mavericks to OS X El Capitan, or EL Capitan to macOS High Sierra, macOS Mojave, etc).

If you have any added details to offer about the “Optimizing Your Mac” message, or perhaps you know how to trigger it manually, do share, or let us know your thoughts in the comments!


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Posted by: Paul Horowitz in Mac OS, Troubleshooting


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  1. Cherith says:

    Hi – I’ve just bought a new Mac book pro & set it up with a back up of my old laptop, when I log in the & put my password in the ‘optimising you mac’ message comes up & I don’t have the option to log it, it’s as if my mac is frozen – any ideas?

  2. William Stewart says:

    I just updated to Maverick on my 27” iMac (probably 4 years old). It starts up, displays the user selection dialogue on top of the Mojave background. I select my user account, type my password, then press Enter. The dialogue changes,to show just my user name and below is a spinning sprocket (there is a separate cursor). The offending message displlays in the upper-right. And, then, nothing… the sprocket continues to “churn.” After perhaps 5 minutes, the mortification disappears. However, the sprocket continues to turn. Any ideas?

    • Dave Big Chief says:

      Download Onyx for Mac.
      Run all the maintenance tasks.

      If it is still not working as required:
      Check in ‘Task Monitor’ what is running to cause the spinning beach ball. Kill that process.
      If it is something you loaded, remove it.

      If it is still not working, reboot holding down cmd+r and reinstall macOS. It should keep all your software and data.

      If still broken. Back-up your data. Reformat the disk and do a clean reinstall.

  3. Donna says:

    So, mine has been optimizing for over 24 hours on my big 27 inch iMac. My computer is about 4 years old and has at least 30,000 photos in iPhoto. Is that why this is taking so long? I usually turn my computer off every night but left it on all night last night. Should I continue to leave it on overnight until this ‘optimizing your mac” goes away? BTW – I skipped El Capitan – I think I upgraded the OS from Leopard to Sierra.

  4. Anonymous says:

    Reinstalling El Capitan will not delete your files, but is recommended only if there are serious system file or boot issues.

  5. Richard says:

    The ‘Optimising your Mac’ message comes up on every single occasion that I reboot my Macbook since installing El Capitan at least 6 months ago. So, many hundreds of hours of this message and it’s still not done? I don’t think so.
    I just want to know how to get rid of it because whatever it says to is doing it’s clearly not working.
    It has been suggested that I reinstall El Capitan and I’d like to know if that is recommended and risk free.

  6. Jason says:

    It runs at a lower priority, like most other house keeping tasks – your apps will take precedence over the optimization.

  7. Avenged110 says:

    Why do I feel like this never used to be an issue in older OS X releases…?

    • PB PM says:

      In older versions of OSX it did the optimizations at a different part of the installation process, (pre 10.5) which proved to be less stable and lead to corruption issues. In 10.5-10.8 these tasks were run in the background and the user was given no notification there of. All that has changed since 10.9 is that Apple is letting users know why their machines might be running a little slower right after a system update is installed.

      Also, pre 10.4 there was no spotlight related activity (since it did’t exist).

      • Avenged110 says:

        Appreciate the reply. While I know that to be true (there just didn’t used to be a notification), I could install/update the OS and have no trouble with performance or power usage. Now doing the same with El Cap, these issues (of which I’m now notified) are very obvious. This is on the same hardware and while things can be subject to change, I never saw it reported that 10.7-10.9 had these issues.

  8. Amy Soldier says:

    Spooky activity, … said as serious as cancer. 🖖🏻

  9. MusicMan :-) says:

    Hi, Is there any way to stop it? I’m a musician using my Mac for live performance and need 100% power available for music.

  10. Roger says:

    Can you run this manually and is it necessary to do so once in a while or just wait? I’ve never seen this notification that I can remember.

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