Why is my Mac so slow? How to find the app to blame

27 October 2026 · 7 min read

A slow Mac is usually not a slow Mac. Most of the time one app or one background process is using far more of the processor, memory or disk than it should, and everything else waits behind it. Find that app, deal with it, and the Mac feels normal again. Restarting works for the same reason: it ends whatever was misbehaving.

Below: how to tell whether one app is to blame, how to find it, the culprits that come up most often, and what to do with each.

First, is it the whole Mac or one app?

Before you look for a culprit, notice where the slowness is.

If one app is slow and the rest of the Mac is fine, the problem is that app. Check whether it shows the spinning beach ball (see the spinning beach ball on a Mac).
If everything is slow, including the pointer, the Dock and switching windows, something is using a large share of the whole Mac, or the Mac is short of memory.
If the Mac was slow only for the first few minutes after starting up, or after a macOS update, it is probably catching up on background work and will settle. Give it an hour before you worry.

Also check the easy things. A Mac with almost no free disk space struggles, so open System Settings, go to General, then Storage, and see how much room is left. And restart it if you have not for weeks. A restart is not a cure for everything, but it clears apps that have been leaking memory for days.

Find the app that is using the most

The fastest way to find the culprit is a list of what is running, sorted by how much each thing is using.

Foreman opens with Control-Shift-Escape, the same keys as Task Manager on Windows. Its Processes page lists apps, background processes and macOS’s own processes in separate sections, with columns for CPU, Memory, Disk, Network, GPU and Power usage. Each app’s figure is a share of the whole Mac, and the Mac’s total sits above each column. Click CPU to sort by processor use, then Memory to sort by memory.

Two details make the list easier to read than a raw one:

An app’s helper processes sit under the app and are added up, so a browser with forty tabs is one row you can open, not forty rows to add in your head.
Common macOS processes have plain names. The process called mds_stores appears as “Spotlight indexing”, with the real name beside it in grey.

Look at the top of the CPU column first. If one app sits far above the others and stays there for more than a few seconds, you have found your suspect. If nothing stands out, sort by Memory and see whether the memory total is near full. Our guide to seeing which app is using the most CPU goes through reading those figures properly.

If you do not want to install anything, the Force Quit window (Option-Command-Escape) will at least show you which apps are marked as not responding. It does not show how much each app is using, though, so it helps with frozen apps and not with slow ones.

The usual culprits

These are the ones that explain most slow Macs.

A browser with too many tabs, or one bad tab. Browsers run each tab, or group of tabs, as its own process, and a page with a video, a live dashboard or a script gone wrong can hold a processor core for as long as it is open. In Foreman, open the browser’s row and look for the one helper that is busy. See how to tell if one browser tab is slowing down your Mac. Closing that tab is better than quitting the whole browser.

Spotlight indexing. After a macOS update, after you copy a large folder onto the Mac, or after you restore from a backup, Spotlight reads every file again so that search works. It shows up as Spotlight indexing and as several Spotlight file readers. It is normal and it ends by itself, usually within hours. Leave the Mac on and plugged in and it will finish.

Photos analysis. After you add many photos, macOS looks through them for faces, scenes and text, in processes with names like photoanalysisd and mediaanalysisd. Foreman describes the first as finding faces, scenes and memories, and says it runs mostly while the Mac is idle. It may run hot for a while and then stop.

A backup. Time Machine runs in the background, and the first backup, or one after a long gap, can take a lot of the disk. It appears as Time Machine backup.

Cloud sync. iCloud Drive, Dropbox and Google Drive all keep files in step with the cloud. If you move or delete a big folder inside one of them, the sync can work hard for a long time.

A video call. Zoom, Teams and Meet use the camera, microphone, video encoding and often the GPU all at once. A Mac that is fine all day can struggle on a call with screen sharing and a blurred background.

An app that is stuck. A program in a loop can sit at a full core of processor use doing nothing useful. It usually shows as one app far above the rest.

Many apps in memory. If the Memory total above the column is high and memory pressure on Foreman’s Performance page is high, the Mac is short of memory and moving data to disk. Quit what you are not using.

What to do about each

Match the action to the cause, from gentle to firm.

Wait, if it is macOS housekeeping. Spotlight, photo analysis, a backup and an update are meant to finish. Ending them rarely helps, because they start again. Leave the Mac plugged in and awake.
Close the tab or the window that is busy, not the whole app, when you can see which one it is.
Quit the app the normal way, with Command-Q, so it can save your work. In Foreman, End Task does the same thing: it asks the app to quit as Command-Q does, so the app can offer to save. Press it again within a minute to force quit.
Force quit only an app that is not responding. Option-Command-Escape opens the Force Quit window, where you pick the app and click Force Quit. You lose unsaved changes, so try quitting normally first.
Do not end macOS’s own processes unless a guide for that specific process tells you to. Ending some of them, such as the window server or the login session, logs you out. macOS restarts many background processes by itself, so ending them often changes nothing.

For an app you want to keep open but that keeps taking more than its share while you work, Foreman has Efficiency Mode. In the background the app runs at background priority and in short bursts, using about a quarter of the processor time it would otherwise take. In front, or while it plays sound, it runs at full speed. Foreman remembers the setting for each app until you turn it off. How much it helps depends on how busy the Mac is. It suits a chat app, a sync client or a build tool that you need open but not right now, and it does not suit anything you are actively waiting on. It also works on macOS’s own background processes that run under your account, such as Media analysis or iCloud Drive, if you would rather they wait while you work.

Slow even when nothing is using much

If the list is quiet and the Mac is still slow, the cause is probably not an app.

Almost no free disk space. Check General, then Storage in System Settings.
Heat. A Mac that gets hot slows itself down to cool off. See why a Mac slows down when it gets warm.
Too much opening at login. If the Mac is slow mainly after startup, look at what starts with it in System Settings, under General, then Login Items & Extensions (called Login Items on macOS 14).
Age. An older Mac with a hard drive, or little memory, is slower on current macOS however well you look after it.

Make it a habit

The cheapest fix is to look when it happens. The next time the Mac slows down, open the list, sort by CPU, then by Memory, and read the top three rows before you do anything. Most of the time the answer is in plain sight, and it is rarely the first thing you would have guessed. Foreman is $12 once, works on up to 3 Macs and is free for 24 hours, if you would like a list like this on hand. Use whichever way suits you; the method is the same: sort, find the one thing, and act on that one thing.