Foreman
Download Buy $12

Why is my Mac slow after a macOS update?

· 5 min read

A Mac is often slow after a macOS update because it is doing catch-up work in the background: rebuilding the Spotlight search index, re-analysing your photos and videos, and syncing iCloud again. This usually runs for a few hours, sometimes up to a day or two on a big library, and then the Mac speeds up by itself. The best thing to do is leave it on and plugged in and let it finish.

This post covers what the background work is, how to confirm it is the cause, and what to do if the slowness does not go away.

What a Mac does after an update

An update replaces system files and changes how some features store their data. Afterwards, several parts of macOS check everything they are responsible for again. None of this is a fault, and you did not do anything wrong. The main jobs are:

  • Spotlight indexing. Spotlight keeps an index of your files so search is fast. After an update it may rebuild or revise that index, reading new and changed files again. The processes involved are mds_stores, which builds and updates the index, and mdworker_shared, which reads the files. On a Mac with a lot of files this takes a while.
  • Photos and media analysis. photoanalysisd finds faces, scenes and memories in your photo library, and mediaanalysisd analyses photos and videos for search, Live Text and Visual Look Up. Photos analysis runs mostly while the Mac is idle, and a larger library takes longer.
  • iCloud catching up. cloudd syncs app data with iCloud and bird syncs iCloud Drive files. If a lot has changed, they upload and download for a while.
  • More updates. softwareupdated checks for and downloads macOS updates, and it may look for further ones after the restart.

Most of these run at low priority in the background and give way when you use the Mac. Even so, on an older Mac, or one with an almost full disk, you will notice them.

How to confirm it

You want to see these processes at work. The Force Quit window (Option-Command-Escape) will not show them, because it lists apps only, so use something that lists background processes.

Foreman does. Open it with Control-Shift-Escape, go to Processes and click the CPU column so the busiest are at the top. Look in the Background processes and System processes sections for names like these:

  • “Spotlight indexing” (mds_stores)
  • “Spotlight file reader” (mdworker_shared or mdworker), often with a count in brackets, such as “Spotlight file reader (4)”, because copies share one row
  • “Photos analysis” (photoanalysisd)
  • “Media analysis” (mediaanalysisd)
  • “iCloud sync” (cloudd) and “iCloud Drive” (bird)

If those sit at the top of the CPU column, with no single app of yours above them, the post-update catch-up is your cause. Foreman shows a plain-English name for each with the real name beside it in grey, so you do not need to know the code names. Each one is also explained in its own post: what is mds_stores and what is mediaanalysisd are the two that appear most after an update.

If the top of the list is an app instead, the update may have left that app misbehaving, and the next section matters less than how to find the app to blame.

How long it lasts

There is no fixed time, and it depends on how much there is to process.

  • A few hours is common on a Mac with a modest library.
  • A day or more can happen with a large photo library, many thousands of files, or a lot waiting to sync with iCloud.
  • Longer than two or three days is not typical. If the same process is still at the top after that, something else is going on, and the last section of this post helps.

Most of this work happens while the Mac is awake. If it sleeps whenever you close the lid, little gets done in the meantime and the total time stretches out.

How to let it finish

  1. Leave it on and plugged in. On a laptop, plug in and leave it overnight with the lid open. A sleeping Mac does little of the work.
  2. Avoid starting more heavy jobs. A large video export or a big download on top of the catch-up will slow both down.
  3. Keep your free disk space healthy. A nearly full disk slows everything down, catch-up work included. You can see what is using space under System Settings > General > Storage.
  4. Do not interrupt it. Ending these processes does not help. macOS starts them again, and the work still has to be done.
  5. Use the Mac normally. Most of these processes give way when you work, so you can carry on.

If you must work while it runs

Sometimes you cannot wait. A few steps reduce the pain.

  • Close the apps you are not using, so the processor has more room.
  • Sort Foreman’s Processes page by CPU and look for an app of yours that is also busy. Quit it with End Task, which asks the app to close normally so it can offer to save.
  • For an app you need open but not at the moment, turn on Efficiency Mode, so in the background it runs at background priority and in short bursts, held to about a quarter of the processor time it would take. In front it runs at full speed. That leaves more room for the system’s catch-up and for the app you are in. The effect depends on how busy the Mac is.
  • Efficiency Mode also works on the catch-up processes that run under your account, such as Media analysis, Photos analysis and iCloud Drive. Use it only while you need the room: the catch-up can take longer while it is on, and turning it off puts them back to full speed at once.

When it does not get better

If a few days have passed and the Mac is still slow:

  1. Restart once. A plain restart is cheap, and it restarts any process that has got stuck.
  2. Check the top of the CPU list again. If the same process is still busy, it may be stuck. Search its name online, from Foreman’s right-click menu, to see whether others have seen it after the same update.
  3. Check for a newer update. Apple often fixes post-update problems in a point release. Look in System Settings > General > Software Update.
  4. Look at your login items. An old helper that does not work with the new macOS can run all the time. System Settings > General > Login Items & Extensions (Login Items on macOS 14) lists them, and how to stop apps opening at login on a Mac walks through it.
  5. Check an older Mac’s limits. A Mac near the oldest the update supports may feel slower afterwards than before. That is the hardware, not a fault.

Foreman is $12 once, covers up to 3 Macs, and is free for 24 hours. A free day is enough to watch one update’s catch-up from start to finish and see when the Spotlight and photo processes calm down.