Why Is My MacBook Running Slowly?

A slow Mac is a symptom. The same sluggishness can come from a runaway app, a nearly full disk, a heap of login items, a hot chassis, or a machine that is simply being asked to do more than it was built for. Each cause has a different fix, and guessing wastes an afternoon.

This guide shows you how to work out which kind of slow you have, using tools built into macOS. You can stop as soon as the Mac feels right again.

Work out what kind of slow it is#

Different symptoms point to different causes. Use this table to decide where to look first.

Try the 30-second diagnosis#

Which kind of slow?

When does the Mac feel slow?

Always, and the fans are loudWhen I switch between appsOnly in the browserOnly right after start-up or an updateEverything lags and the disk is nearly full

Check Activity Monitor#

Activity Monitor is the single most useful tool for this job. Open it from Applications → Utilities, or press ⌘ Space and type its name.

Read the CPU tab#

1. Click the CPU tab.
2. Click the % CPU column header so the busiest processes are on top.
3. Watch for a few seconds. Brief spikes are normal. What you're looking for is a process that stays high.

If one process sits at a high percentage and you don't recognise a good reason for it, that's your lead. Note its name, then search for it. Some names are system processes you should leave alone. If it belongs to an app you installed, quitting or updating that app is the next step. Our guide to fixing high CPU usage covers the common offenders, and WindowServer has its own explanation.

Read the Memory tab#

Click Memory. Ignore the "Memory Used" number on its own; look at the Memory Pressure graph at the bottom.

• Green: macOS has plenty of room. Memory is not your bottleneck.
• Yellow: the system is compressing memory to keep up. Things may feel slightly slower.
• Red: the system is under heavy pressure and swapping to disk. This is a genuine cause of slowness.

If pressure is yellow or red, sort by the Memory column to see which apps are using the most, and close what you aren't using. If it's red most of the day, your workload probably needs more memory than the Mac has.

Force quit apps that are not responding#

An app that is frozen or beach-balling can drag the rest of the system with it. To force it to quit:

1. Press ⌘ ⌥ Esc to open the Force Quit window.
2. Select the app marked Not Responding, or any app you suspect.
3. Click Force Quit.

You can also open the Apple menu and choose Force Quit, hold ⌥ and right-click an app's Dock icon, or select the process in Activity Monitor and click the stop button. Force quitting loses any unsaved changes in that app, so give it a minute to recover first if it is merely busy.

Make sure there is room on the disk#

Macs use free disk space as overflow when memory runs short, so a nearly full drive slows everything. Apple gives no official threshold, so treat a handful of gigabytes as tight.

Open System Settings → General → Storage and look at the available space. If it's tight, the System Data category is often the cause; our guide to why System Data takes up so much space explains how to look inside it and what's safe to remove.

Trim what starts with your Mac#

Every app that launches at login uses memory and CPU from the moment you sign in.

1. Open System Settings → General → Login Items & Extensions.
2. Under Open at Login, remove anything you don't need running all the time. Use the minus button.
3. Check the Allow in the Background list too. Some apps run helper processes even when you haven't opened them.

Don't remove anything you don't recognise without searching for it first. Security software, backup tools, and hardware drivers also live here.

Look at your browser#

For many people, the browser is where most of the memory goes.

• Close tabs you aren't using, or use a tab-suspending feature if your browser has one.
• Disable extensions one at a time. A single heavy extension can make every page slower.
• In Safari, use Activity Monitor to find which web page is expensive. In Chrome, open Window → Task Manager to see the cost of each tab and extension.

Give background work time to finish#

After a macOS update, a big file import, or connecting a large photo library, the Mac does work in the background: Spotlight indexing, Photos analysis, and iCloud sync. In Activity Monitor you may see processes such as mds, mdworker, or photoanalysisd with high CPU. This is usually temporary. Leave the Mac plugged in and awake for a few hours before assuming something is wrong.

Rule out heat#

If the Mac is warm and the fans are loud, it may be slowing itself down to stay cool. This is called thermal throttling. Check that the vents aren't blocked, avoid using it on soft surfaces, and see our guide to fixing MacBook overheating.

If it's still slow#

These steps go beyond the quick fixes. Make a backup before the later ones.

1. Test with Safe Mode. Safe Mode loads only essential software, which tells you whether a third-party extension is the cause. On an Apple silicon Mac, shut down, then press and hold the power button until startup options appear, select your disk, hold ⇧, and choose Continue in Safe Mode. On an Intel Mac, hold ⇧ as it starts up.
2. Run Apple Diagnostics. On Apple silicon, press and hold the power button until startup options appear, then press ⌘ D. On Intel, hold D while starting up. It reports hardware problems it finds.
3. Try a new user account. In System Settings → Users & Groups, add a test user and use it for a while. If the Mac is fast there, the problem is in your original account's settings or files, not the hardware.
4. Reinstall macOS. From Recovery you can reinstall macOS without erasing your files. It replaces system files and leaves your data in place. Back up first.

Is it just old?#

Sometimes none of the above finds a cause because the Mac is doing exactly what it can. A model that is several years old, or one with a small amount of memory, may struggle with current browsers and apps. If memory pressure is regularly red and storage is nearly full even after cleanup, the honest answer may be a hardware upgrade where possible, or a newer Mac.

What we don't recommend#

• "Speed-up" apps that promise instant fixes. Almost everything they do, you can do yourself with the steps above. Our Best Mac Optimization Software guide tests their claims one by one; until then, be sceptical of performance claims.
• Deleting system folders. It's rarely the fix and can cause new problems.
• Resetting everything first. Work from the least disruptive step to the most.

Frequently asked questions#

Why is my MacBook slow after an update?#

Updates trigger indexing and background tasks that use CPU and disk for hours. Leave the Mac on and plugged in. If it's still slow after a day or two, work through the Activity Monitor steps.

How do I know if my Mac needs more RAM?#

Watch the Memory Pressure graph during your normal work. If it spends a lot of time yellow or red, you're short of memory. If it stays green, more RAM won't help.

Does a restart really help?#

Yes, often. It clears temporary files, resets virtual memory, and ends processes that have been running for days.

Is it safe to quit processes in Activity Monitor?#

Quit processes that belong to apps you recognise. For anything else, search the process name first. Quitting a system process can cause unexpected behaviour until you restart.