How To Check CPU Usage On Mac
When your Mac starts lagging or the fans kick on high, the first thing you need to check is your processor. The CPU is the engine of your computer. If a single app is using 100% of the CPU, every other app has to wait in line, causing your entire system to stutter and freeze.
Here is the fastest way to check your CPU usage using built-in macOS tools and how to actually understand the numbers you are looking at.
Step 1: Open Activity Monitor
Apple includes a free utility on every Mac called Activity Monitor. It is the equivalent of the Task Manager on Windows.
The fastest way to open it is using Spotlight Search:
- Press Cmd + Space on your keyboard to open Spotlight.
- Type "Activity Monitor" and press Enter.
Alternatively, you can open a Finder window, go to the Applications folder, open the Utilities folder, and double-click Activity Monitor.
Step 2: Read the CPU Tab
When Activity Monitor opens, click the CPU tab at the top of the window. You will see a massive, constantly moving list of every single process running on your Mac.
To make sense of it, click the column header labeled % CPU. This will sort the list so the most demanding apps are pinned to the top.
- Under 10%: Completely normal background activity.
- 10% to 50%: Normal for an app you are actively using, like a web browser rendering a heavy webpage or a video call.
- Over 90%: The app is working extremely hard. If you are exporting a video or playing a game, this is normal. If you are just looking at a blank document and an app is stuck at 99%, it has frozen and is hoarding resources.
What this process is
WindowServer is the part of macOS that draws everything you see. Every window, every menu, every animation and every pixel pushed to an external display goes through it. It is not an app you installed and it cannot be quit.
Why it is using CPU right now
At 7.3% it is doing ordinary work. WindowServer rises with the number of pixels it has to move, so a large or scaled external display, a wallpaper that animates, and windows being dragged all push it up. It settles as soon as the screen stops changing.
Recommended Actions
- No action neededSingle-digit CPU for WindowServer on a machine driving its own display is normal and costs nothing worth reclaiming.
- Look again if it sits above 30% while nothing is movingSustained high WindowServer with a still screen usually points at a scaled resolution on an external display, or at transparency effects, both of which are settings you can change.
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Step 3: Understand System vs User Load
At the very bottom of the Activity Monitor window, you will see a small box with three metrics: System, User, and Idle.
- User: The percentage of the CPU being used by apps you opened, like Chrome, Spotify, or Word.
- System: The percentage being used by core macOS background processes.
- Idle: The percentage of the CPU that is completely free and waiting for instructions.
If your Mac is lagging and the "System" percentage is extremely high, you might have a rogue background process. Look for confusing names like mds_stores or kernel_task at the top of your list. We explain these in our guides on What is kernel_task? and What is WindowServer?. Spotlight's mdworker_shared and the Photos agent photoanalysisd are two more common ones.
Step 4: Force Quit Stuck Apps
If you spot an app that is clearly stuck at 100% CPU and causing your Mac to freeze, you can kill it directly from this window.
- Click the name of the misbehaving app in the list to select it.
- Click the small X button at the top of the Activity Monitor window.
- Click Force Quit in the confirmation popup.
The app will immediately close, releasing the CPU and instantly speeding up your Mac.
A Better Way to Monitor Your CPU
Checking Activity Monitor is great when your Mac is already frozen. But by the time you open it, the damage is done.
If you want to keep an eye on your system health and catch rogue apps before they freeze your computer, you need MacStats.
MacStats is a native menu bar app that gives you a continuous, real-time look at your CPU usage. You do not have to open a separate app: the data is always right there in your menu bar, and our guide to showing CPU usage in the Mac menu bar shows how to set it up.
With MacStats Pro, you also get the Process Explainer. When one of your own apps or processes is using a lot of CPU, click it in the MacStats dashboard for a plain-English explanation of what it is doing and whether it is safe to quit. MacStats lists the processes that run under your account; system processes such as kernel_task and WindowServer still need Activity Monitor.
macOS reports normal memory pressure.
↓8.03KB Live Activity
- 1MacStats16.4%›
- 2corespotlightd7.3%›
- 3Siri AI6.5%›
- 4dataaccessd2.3%›
- 1Google Chrome486.2 MB›
- 2Chrome Helper380 MB›
- 3OrbStack Helper373.6 MB›
- 4cmux296.7 MB›
MacBook Air, Apple M4 | 16 GB RAM | macOS 27.0
Stop waiting for your Mac to freeze. Download MacStats for Free and get continuous visibility into your CPU. Check out how it transforms your workflow in our guide on MacStats vs Activity Monitor.
Frequently asked questions
How do I see what is using my CPU on Mac?
Open Activity Monitor from the Applications folder, click the CPU tab, and sort by the % CPU column to see which apps are using the most processing power.
Is high CPU usage bad for my Mac?
High CPU usage is normal when running demanding apps like video editors or games. However, if a background app gets stuck at 100% CPU when you are doing nothing, it will cause your Mac to overheat and slow down.