Mac Slow After Update? Causes Ranked and How to Fix Each

If your Mac is slow after an update, the most likely reason is that macOS is still doing post-install work in the background: rebuilding the Spotlight index, re-analyzing your Photos library and re-syncing iCloud. Leave the Mac plugged in and awake for a day or two and the slowdown usually fades on its own; if it does not, the cause is almost always an app that needs its own update, login items that came back, a tighter disk or the tabs and apps you were already running.

This guide applies to updates to macOS 26 Tahoe, macOS 15 Sequoia and macOS 14 Sonoma, including point releases. It starts with a two-minute check that tells you which situation you are in, then walks through the causes from most to least common, each with its fix. For general slowness that has nothing to do with an update, see Why Is My Mac So Slow? instead.

The quickest check: look at Activity Monitor

Before changing any setting, find out what is actually using the processor. The process names tell you whether to wait or to act.

Open Activity Monitor from Applications > Utilities, or press Command-Space and type Activity Monitor.
Click the CPU tab, then click the % CPU column header so the busiest processes are at the top.
Watch the top five names for a minute.
Click the Memory tab and look at the Memory Pressure graph at the bottom. Green is fine, yellow means the Mac is compressing and swapping, red means it is short of memory.

Process at the top	What it is doing	What to do
mds, mds_stores, mdworker	Spotlight rebuilding its search index	Wait; keep the Mac on power
photoanalysisd, mediaanalysisd	Photos re-scanning faces, scenes and text	Wait; it works fastest when the Mac is idle and plugged in
bird, cloudd, fileproviderd	iCloud Drive and other cloud folders re-syncing	Wait; check your network if it lasts days
backupd	Time Machine catching up after the update	Let the backup finish
softwareupdated	Downloading or preparing another update	Let it finish, then restart if asked
An app name, or many Google Chrome Helper (Renderer) entries	A third-party app or your browser tabs	See causes 2, 3 and 6 below

If the top of the list is all Apple system processes, the honest fix is patience. Plug in, leave the lid open overnight with the screen allowed to sleep, and check again the next day. Restarting repeatedly does not skip this work; it only interrupts it. For more on reading the Memory tab, see How to Check RAM Usage on Mac.

Mac slow after update: the causes, most common first

1. Spotlight, Photos and iCloud are re-indexing

A major update often triggers a full Spotlight re-index and a fresh Photos analysis pass. On a Mac with a large home folder or a big photo library this can take anywhere from a few hours to a couple of days, and it makes the fans spin and the battery drain faster in the meantime.

Fix: wait, on power. If mds_stores is still near the top after three or four days, rebuild the index once:

Open System Settings > Spotlight (Siri & Spotlight on Sonoma).
Click Search Privacy (Spotlight Privacy on older versions).
Add your startup disk to the list, wait a few seconds, then remove it. Spotlight starts a clean index, which again takes a while but should finish this time.

2. Apps that are not ready for the new macOS

Apps built for the previous version can misbehave after an update: a sync tool that loops, a menu bar utility that pegs a core, an old Intel-only app running under Rosetta. An app stuck at high % CPU after an update usually needs its own update.

Open the App Store and click Updates.
For apps from outside the App Store, open each one and choose App name > Check for Updates, or look in its settings.
Update your browser too: in Chrome, choose Chrome > About Google Chrome.
In Activity Monitor, right-click a column header and turn on Kind. Apps marked Intel run through Rosetta on Apple silicon and use more processor time than native versions.

3. Login items and background tasks that came back

Updates sometimes re-enable helpers, and newly updated apps can register fresh background items. macOS shows a Background Items Added notification when this happens, which is easy to dismiss without reading.

Open System Settings > General > Login Items & Extensions (Login Items on Sonoma).
Remove anything under Open at Login you do not need at startup.
Under Allow in the Background, switch off helpers for apps you rarely use.

4. Less free disk space than before

The installer, Time Machine local snapshots and leftover caches can eat tens of gigabytes. When free space drops below roughly 10% of the drive, macOS has less room for swap and caches, and everything feels sticky.

Check System Settings > General > Storage. A large System Data figure often shrinks by itself once Time Machine finishes and old snapshots expire. If it does not, delete large files you no longer need, empty the Trash and move archives to an external drive.

Less common causes worth checking

5. New visual effects or features on an older Mac

macOS 26 Tahoe introduced the Liquid Glass design, with more transparency and blur. On older or lower-spec Macs, especially Intel models, turning down the effects can make windows and Mission Control feel smoother.

Open System Settings > Accessibility > Display.
Turn on Reduce transparency.
Optionally turn on Reduce motion as well.

On Macs that support Apple Intelligence, an update can also start downloading or refreshing on-device models. That finishes on its own; if you do not use the features, you can manage them in System Settings > Apple Intelligence & Siri.

6. The update exposed a load you already had

Sometimes the update only shifted the baseline a little, and the real weight is the same 60 browser tabs, chat apps, cloud sync tools and dev containers you ran before. If the system processes have calmed down but Memory Pressure is still yellow or red and the CPU list is full of app names, the update is no longer the cause. How to Clear RAM on Mac covers the quick manual fixes, and the Mac Ninja section below covers the automatic one.

7. A third-party extension that conflicts with the new version

Old system extensions, VPN clients, antivirus tools and audio drivers are the usual suspects. Safe Mode, below, tells you quickly whether something like this is involved.

Test in Safe Mode to rule out third-party software

Safe Mode starts the Mac without third-party login items and extensions. If the Mac feels clearly faster there, something you installed is the cause, not macOS itself.

On a Mac with Apple silicon

Choose Apple menu > Shut Down.
Press and hold the power button until Loading startup options appears.
Select your startup disk, hold Shift, and click Continue in Safe Mode.

On an Intel Mac

Choose Apple menu > Restart.
Press and hold Shift immediately until the login window appears.

Safe Mode shows Safe Boot in the menu bar, and the first startup is slower than usual while it checks the disk. Use the Mac for ten minutes, then restart normally. If Safe Mode was fast, go back to cause 2 and cause 3 and remove login items one at a time until you find the culprit.

If the Mac is just as slow in Safe Mode after several days, back up with Time Machine and reinstall macOS from Recovery (on Apple silicon, hold the power button, choose Options, then Reinstall macOS). This keeps your files and apps and replaces only the system.

When the slowdown is really tabs and background apps

Once the post-update indexing is done, the most common reason a Mac still feels slow is the everyday load: dozens of idle browser tabs holding memory, and background apps grabbing the processor while you work in something else. Mac Ninja is a menu bar app built for exactly that, and it never closes an app or a tab to do it.

Idle tabs sleep. Tabs untouched for 15 minutes (adjustable) are unloaded in Chrome, Brave, Edge, Arc, Vivaldi, Opera, Comet, Dia, Chromium and Safari (Lite mode). They stay in the tab strip and reload when clicked. The visible tab, pinned tabs, tabs playing sound and incognito windows are skipped. The free Mac Ninja Helper extension uses Chrome's native tab discarding.
Background hogs are calmed, not killed. Foreground Boost moves apps that hog the processor or the disk to macOS's own low-priority lane while you work, and gives them full speed the instant you switch to them. It never slows apps playing or recording audio.
A plain-English answer. Right-click the menu bar ninja for a dashboard with live rings for the front app, memory and the fast cores, plus a Why does my Mac feel slow right now? reading. On macOS 26 Tahoe it is phrased by Apple Intelligence on the device, so nothing leaves the Mac.
AI agent cleanup. With the helper, tabs left behind by AI browser agents such as Claude in Chrome are closed after the whole agent session has been idle for 8 hours (configurable, can be switched off).

Who it is not for: if Activity Monitor shows mds_stores or photoanalysisd, wait instead; no app should interrupt that. Mac Ninja cannot make an old processor faster, and on a nearly full disk it frees room only by offloading apps unused for 60 days, not photos or videos. If those are your problem, a cleanup or a hardware upgrade is the right answer.

It runs on Apple silicon and Intel, comes with a 7-day free trial, then costs $9.99 per year or $24.99 once, each for up to 3 Macs, with a 14-day money-back guarantee. See pricing, and support for setup and Chrome access. For a broader comparison, read Best Mac Cleaner in 2026.

How to stop it coming back next update

Most post-update slowdowns are predictable, so a little preparation makes the next one shorter. The biggest wins are free space and timing.

Free at least 20 GB first. Updates need working room, and a roomier disk recovers faster afterward.
Back up with Time Machine before updating, so the post-update backup is small.
Update your apps before macOS. Developers usually ship compatibility fixes around a major release.
Consider waiting for the first point release of a major version (for example x.1) if you depend on older apps.
Install in the evening, on power, and leave the Mac plugged in overnight so indexing finishes while you sleep.
Read the Background Items Added notification and check Login Items & Extensions the next day.

If your Mac is a MacBook Air, which has no fan and often 8 GB of memory, the indexing period can feel worse; MacBook Air Slow? has fixes specific to that model.

What to do next

Open Activity Monitor now and note the top five CPU processes.
If they are Apple system processes, plug in and give it until tomorrow.
If they are apps, update them and trim Login Items & Extensions.
If tabs and background apps are still dragging the Mac down after that, try Mac Ninja free for 7 days and let it handle them without closing anything.

Frequently asked questions

How long is a Mac slow after an update?

Usually a few hours to two days. After a major macOS update, Spotlight rebuilds its index and Photos re-analyzes your library, and both take longer on Macs with large libraries or little free space. Keep the Mac plugged in and awake overnight to let the work finish. If it is still slow after three or four days, check Activity Monitor for an app causing the problem.

Why is mds_stores using so much CPU after an update?

mds_stores is the Spotlight indexing process, and a macOS update often triggers a full re-index of your disk. High CPU use for a day or two is normal. If it continues for several days, rebuild the index by adding your startup disk to the Spotlight privacy list in System Settings, waiting a few seconds, and then removing it again.

Should I downgrade macOS if my Mac is slow after updating?

Rarely. Downgrading requires erasing the Mac and restoring from a backup made before the update, which is time-consuming and risky. Most post-update slowness ends once indexing finishes or after you update incompatible apps. If the Mac stays slow in Safe Mode for days, reinstalling the current macOS from Recovery is a gentler step that keeps your files and apps.

Does restarting help a Mac that is slow after an update?

One restart can clear a stuck process or finish installing an update, so it is worth doing once. Restarting repeatedly does not help with background indexing, though, because Spotlight and Photos simply resume where they left off. The better fix is to leave the Mac plugged in and idle so the work finishes faster.

Can a memory cleaner fix a slow Mac after an update?

Not during the indexing period, because that work is processor and disk activity that macOS needs to finish. Once it is done, an app like Mac Ninja helps if the remaining slowdown comes from idle browser tabs or busy background apps. It cannot speed up an old processor or free space taken by photos and videos.