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Guide · Slow Mac

Why is my Mac so slow? How to find the cause and speed it up

By the AI Repair team · Updated

A slow Mac is rarely a worn-out Mac. Usually one thing is holding it back, and the tools to find it are already on your Mac. This guide goes from the quickest fix to the rarer causes, explains what each step does, and lists the popular advice that won’t help.

In short

Most slow Macs have one of a few causes: an app or web page keeping the processor busy, more open than the memory can hold, catch-up work after a macOS update, too many apps starting at login, heat, or a nearly full disk. Restart first. If it’s still slow, open Activity Monitor: its CPU and Memory tabs show what is holding your Mac back.

1. Restart your Mac

It sounds too simple, but it often works. A restart ends apps and background tasks that have got stuck, and gives the memory a fresh start. Save your work, then choose Apple menu › Restart.

Wondering how long it has been? Hold the Option key, choose Apple menu › System Information, then click Software: the line Time since boot says how long your Mac has been running. Apple gives no rule for how often to restart, but if your Mac has been on for weeks and feels sluggish, a restart is the place to start.

2. Find what’s slowing it down

Activity Monitor is the Mac’s own task manager. It shows every app and background process, and how much of the processor and memory each one uses.

  1. Press ⌘ Space, type Activity Monitor and press Return.
  2. Click the CPU tab. The busiest apps should be at the top; if they aren’t, click the % CPU column heading.
  3. Look for an app near the top that you aren’t using, or one marked (Not Responding) in red.

An app that sits at a high percentage while you’re doing nothing with it, often a web browser with many pages open, is a likely culprit. To quit it, select it, click the Stop button (the ✕ at the top of the window) and choose Quit. Use Force Quit only if Quit doesn’t work: it can lose unsaved changes. You can also force an app to quit with Option ⌘ Esc, the same as Apple menu › Force Quit.

Leave processes you don’t recognize alone at first, especially ones owned by the system, such as WindowServer or kernel_task. They do work for the whole Mac. A busy kernel_task has its own explanation, below.

3. Check whether your Mac is short of memory

Click the Memory tab in Activity Monitor and look at the Memory Pressure graph at the bottom. Apple explains its colours like this (Apple’s guide):

  • Green: your Mac is using its memory efficiently. Memory isn’t the problem.
  • Yellow: your Mac might eventually need more memory.
  • Red: your Mac needs more memory than it has.

When memory runs short, macOS moves things it isn’t using to the disk. That shows as Swap Used, and it’s slower than real memory. If the graph is yellow or red, quit apps you aren’t using and close browser windows and tabs you don’t need.

A Mac with lots of “free” memory isn’t faster for it: macOS keeps memory busy on purpose, and Apple notes that freeing it doesn’t necessarily improve performance. Watch the pressure graph, not the free number. To see how much memory your Mac has, choose Apple menu › About This Mac. On a Mac with Apple silicon the memory can’t be upgraded later, so if the graph is red every day, your Mac may simply have less memory than the way you use it needs.

4. Stop apps from opening at login

Many apps add themselves to the list of things that start with your Mac: cloud storage, updaters, chat apps. Each one takes memory and processor time from the moment you log in. Where the list lives depends on your macOS:

  • macOS Sequoia or later: System Settings › General › Login Items & Extensions
  • macOS Ventura or Sonoma: System Settings › General › Login Items
  • macOS Monterey: System Preferences › Users & Groups › your name › Login Items

Not sure which macOS you have? Choose Apple menu › About This Mac.

Under Open at Login, select an app you don’t need straight away and click the remove button (–). It stays installed; it just won’t start by itself. Below that list, apps that run in the background have switches you can turn off. Leave on anything you rely on, like a backup app or your security software.

To test whether login items are the problem, log out, then hold Shift as you click Log In and keep holding it until the Dock appears. Your Mac starts this once without opening them.

5. Slow after a macOS update? Give it a day

After a macOS update, your Mac has catch-up work to do. Spotlight rebuilds its search index, Photos analyzes your library again, and iCloud may sync. Apple says Spotlight indexing alone “can take hours or even days” (Apple’s note on indexing). In Activity Monitor this shows as processes such as mds_stores, mdworker and photoanalysisd working hard.

This is normal and it ends by itself. It finishes sooner when your Mac is plugged in, connected to the internet and left awake while you’re not using it, for example overnight with the lid open.

Then update your apps too. Apps that haven’t caught up with a new macOS can slow down the whole Mac: just after macOS Tahoe arrived in 2025, some popular apps, such as Slack, made Macs lag until they were updated. Update apps from the App Store or from each app’s own menu, and macOS itself from System Settings › General › Software Update (System Preferences › Software Update on Monterey).

6. Slow and the fan is loud? Check for heat

If your Mac gets slow when it’s hot, or a process called kernel_task is near the top of Activity Monitor, heat is the likely cause. kernel_task is part of macOS. When the processor gets too hot, it takes processor time away from apps so the chip can cool down, even if the Mac doesn’t feel hot to you. Apple is clear that kernel_task doesn’t cause the heat; it reacts to it (Apple on kernel_task).

  • Quit the apps using the most processor time (step 2). That’s Apple’s own fix.
  • Use a laptop on a hard, flat surface, not on a bed, cushion or your lap, and keep its vents clear.
  • Keep it out of direct sun and away from heaters. In a warm room the fans start sooner.

If the fans on a Mac with Apple silicon race while it isn’t doing anything, Apple suggests closing and opening the lid of a laptop, or restarting (Apple on fans).

7. Make sure the disk isn’t nearly full

Apple lists a startup disk without enough free space as one cause of a slow Mac (Apple’s guide to a slow Mac). It gives no exact figure, but macOS needs room on the disk for swap (step 3), for temporary files and for updates. Choose Apple menu › System Settings › General › Storage to see how much is free, and use the recommendations there to make room. On Monterey, it’s Apple menu › About This Mac › Storage.

Our guide Mac storage full? How to free up space shows what to remove safely, and what System Data is.

8. Close tabs and remove extensions you don’t use

For many people, the slow part is the web browser. Every open tab can use memory and processor time, and some pages keep working in the background. Close tabs you don’t need, and quit apps you aren’t using, which Apple recommends too.

Browser extensions can also slow things down. In Safari, choose Safari › Settings (Safari › Preferences on Monterey), click Extensions, and turn off or uninstall any you don’t use. Other browsers have a similar list in their settings.

9. Check that Low Power Mode isn’t on

Low Power Mode makes a Mac use less energy, and to do that it manages performance. It’s great for a long day on battery, but if it’s always on, your Mac can feel slower. Check it in System Settings › Battery, next to Low Power Mode (System Preferences › Battery on Monterey). You can set it to work only on battery.

10. Try safe mode

Safe mode starts your Mac without some login items and extensions, checks the startup disk and clears some system caches, which macOS creates again as needed. If your Mac is fast in safe mode, something that normally starts with it is the cause. On a Mac with Apple silicon (Apple’s steps):

  1. Shut down your Mac.
  2. Press and hold the power button until the startup options appear.
  3. Select your startup disk, then hold Shift and click Continue in Safe Mode.
  4. When the login window appears, you’ll see “Safe Boot” at the top right. Then log in.

On an Intel Mac, hold Shift as it starts up and let go at the login window. Use your Mac for a while, then restart normally to leave safe mode. If it’s still slow even in safe mode, Apple’s next step is to reinstall macOS, which keeps your files. Back up with Time Machine first, and follow Apple’s steps carefully: the same screens also offer to erase the disk, which you don’t want.

When it’s the hardware

If none of this helps, the Mac itself may be the limit, or a part may be failing. Two built-in tools can tell you more:

  • Apple Diagnostics tests the hardware. On a Mac with Apple silicon, shut down and disconnect everything except the keyboard, mouse, display, Ethernet cable and power. Press and hold the power button until Options appears, let go, then press and hold ⌘ D (Apple’s steps).
  • Disk Utility (in Applications › Utilities) can check the disk for errors with First Aid.

Older Macs with a spinning hard drive and little memory struggle with today’s apps, whatever you do. For a repair, Apple Stores and Apple Authorized Service Providers are the ones Apple’s warranty and AppleCare cover. Take any reference code from Apple Diagnostics with you.

Advice you can skip

Search for “speed up Mac” and you’ll find these tips again and again. On a modern Mac they don’t help, and some do harm:

  • Reset the SMC. On a Mac with Apple silicon the SMC resets by itself, and Apple says even on Intel Macs it’s for problems with fans, power and battery, not speed.
  • Reset NVRAM or PRAM. Apple says the steps don’t apply to Macs with Apple silicon and aren’t needed there.
  • Delete all your caches. Apple never asks you to delete caches by hand. Apps rebuild them, so for a while they get slower, not faster.
  • Use a “RAM cleaner”. Free memory doesn’t make a Mac faster. Memory pressure is what matters.
  • Rebuild the Spotlight index. It’s for search that doesn’t work, and it starts hours or days of indexing.
  • Turn off FileVault. On a Mac with Apple silicon the disk stays encrypted anyway, so you lose protection and gain nothing.
  • Quit kernel_task. It’s the Mac’s heat brake. It backs off by itself as the processor cools.

Common questions

Why is my Mac so slow all of a sudden?

A sudden slowdown usually has a sudden cause: a macOS update that is still indexing, an app or web page that got stuck using the processor, or heat. Check Activity Monitor’s CPU tab first. If it was just updated, give it a day, plugged in and awake.

Why is my Mac slow when I have plenty of storage?

Free space is only one cause, and often not the main one. With plenty of storage, look at memory pressure, the busiest apps in Activity Monitor, your login items and heat. Too many open apps and tabs on a Mac with 8 GB of memory is a very common reason.

Do Mac cleaner apps make a Mac faster?

Rarely. Cleaners mostly free disk space by deleting caches and leftover files, which helps a nearly full disk but doesn’t fix a busy app, a lack of memory or heat. Deleted caches also grow back. Our guide Do you need a Mac cleaner app? goes into the details.

Will more memory make my Mac faster?

Only if memory pressure is often yellow or red. On a Mac with Apple silicon the memory is built in with the chip and can’t be added later; some older Intel Macs can take more. Hold Option, choose Apple menu › System Information and click Memory: if Upgradeable Memory says No, or no memory slots are listed, it can’t be upgraded.

Can a virus make my Mac slow?

It can, but it’s an uncommon cause on a Mac. More often it’s adware: a browser add-on that shows pop-ups or changes your home page, which you can remove in the browser’s extension settings. macOS has its own malware protection that updates by itself, so keep macOS up to date.

Should I shut down my Mac every night?

There’s no need. Sleep uses very little power and your Mac wakes straight away, ready where you left off. Restart when your Mac feels slow, after an update, or when an app misbehaves.