How to fix the kernel_task high CPU issue on your Mac?

By Connie | Posted to Home > Howto, on October 14th, 2021

Summary: This post offers efficient solutions to solve the kernel_task high CPU usage issue on your Mac. After that, your Mac won't run slowly, overheat, crash, etc.

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It's troublesome once your Mac begins to run slowly, keeps overheating, or the fan sounds so loud. You may consider it is caused by running too many apps simultaneously or running the Mac computer too long.

However, turning off all the apps or even restarting the Mac changes nothing. The slow computer probably has the kernel_task high CPU usage issue. If you ignore it, your Mac may experience crashes or even won't boot up later.

Here, in this article, we offer you a thorough analysis of the kernel_task high CPU usage problem and the most efficient solutions to fix it.

Fix kernel_task high CPU usage issue

How to fix your Mac's kernel_task high CPU usage?

What is kernel_task on Mac Activity Monitor?

Mac kernel_task, a label in Activity Monitor, represents various activities that make the rest of your Mac machine work.

These activities proceed flows through the kernel that sitting between your hardware and the software that you run. So, that's why they are generally named as kernel_task in Activity Monitor.

The causes of kernel_task high CPU usage

Usually, kernel_task takes up less than 10% of the CPU. And sometimes, it reaches up to 60%. It's also okay. But when the kernel_task takes up nearly 100% of your CPU or over from minutes to hours, problems happen, such as your Mac machine runs slowly.

kernel_task CPU usage in Activity Monitor

As kernel_task is a label of a series of processes, it's hard to immediately find the culprit that causes your kernel_task with high CPU usage.

After research, we have summarized the common reasons for the kernel_task high CPU usage issue:

  1. Charge your Mac for a long time.
  2. Run too many apps at the same time.
  3. Install a buggy Adobe Flash Player on Mac.
  4. Enable third-party extensions (or called kext).
  5. The internal fan of your Mac does not work properly.
  6. Your Mac is attacked by some malware.

How to fix kernel_task high CPU usage

Unlike other programs that can be force quitted from Activity Monitor, you can't stop kernel_task on Mac as it stands for a series of activities.

According to the reasons we've analyzed above, you can troubleshoot kernel_task with high CPU usage through the following solutions.

Cool your Mac computer

Apple has suggested that users should use their Mac devices in the acceptable environments with operating temperatures between 50° — 95°F or 10° — 35°C. Or else, it will lead to high chassis temperature, and consequently, a high CPU usage to regulating the temperature.

Hence, you can try to disconnect your Mac from charging, unplug the unnecessary peripherals, and move your Mac to a cooling environment. After your computer cools down, check if the CPU usage of kernel_task reduces.

Quit inessential processes in Activity Monitor

Usually, the more programs you run, the more CPU it will take up. Consequently, your Mac slows down. You can open Activity Monitor to quit the inessential processes one by one.

  • Search Activity Monitor in the Spotlight Search box on the upper right corner of your screen. Then, double-click to open it.
  • Select a process and click the icon at the upper left corner of the Activity Monitor window.
  • Click Quit.
  • Repeat the above operation on each inessential process.

Quit processes in Activity Monitor

When you quit all the unnecessary apps or programs, shut down your Mac and wait a moment. Then, restart your Mac to check if it gets on the right track.

Reset SMC

SMC (System Management Controller) on your Mac controls power management and hardware like battery, fan, etc. If your fan lasts running at high speed and then brings about the kernel_task high CPU usage issue, resetting SMC may fix it.

Reset SMC on MacBook Pro or MacBook Air:

  • Shut down your Mac.
  • Press down the Control + Option + Shift (on the right side) keys. Then hold the power button.

Note: For MacBooks without a T2 chip, use the left Shift key instead.

  • Release the four keys after ten seconds.
  • Turn on your Mac.

Reset SMC on iMac and Mac mini:

  • Shut down your Mac and unplug the power cord.
  • Wait 10 seconds and then replug the power cord.
  • Wait 5 seconds and then press the power button to turn on your computer.


NVRAM (Non-volatile random-access memory) is a small amount of memory that stores OS-related settings to keep your Mac perform properly and boot up quickly.

When kernel_task consumes high CUP and leads to improper Mac performance, resetting NVRAM may fix the trouble.

Here's how to reset NVRAM:

  • Turn off your Mac.
  • Press down the Option + Command + P + R keys during your Mac reboots.
  • Reset NVRAM on your Mac
  • Release the keys when hearing the second startup sound from your Mac. If you use a T2-based Mac, release the keys when the Apple logo appears and disappears twice.

If you use an Apple M1 Mac, there's no need to manually reset NVRAM. It will auto-resets if needed every time you start up your Mac.

Boot your Mac into Safe Mode

Some software enables third-party extensions for managing hardware. This has the risk of causing kernel_task with high CPU usage.

So, you can boot your Mac into Safe Mode, which only loads the required extensions and drivers.

To boot an Intel-based Mac in Safe Mode:

  • Completely turn off your Mac.
  • Hold down the Shift key when restarting your Mac.
  • Release the Shift key until you see the login window.

To boot an M1 Mac in Safe Mode:

  • Shut down your Mac.
  • Hold down the power button until the startup options and the Options icon appear.
  • Select your startup disk and then hold down the Shift key and click Continue in Safe Mode.
  • Release the Shift key.

If your Mac performs well in Safe Mode, the recently installed third-party software is the culprit. You can remove it from your Mac and restart the computer. Then, your Mac will back to normal.

Update software

Sometimes, some bugs may appear after you upgrade to the first version of the new OS. Or you haven't upgraded your macOS for a long time, resulting in the software not working well with the hardware anymore.

Later, problems like kernel_task with high CPU usage pop up. Therefore, proceed a software update can fix the issue.

All you need to do is open System Preferences in the Apple menu. Then, choose Software Update to check if there's any new version released. If there has, update your Mac to the latest version.

Proceed Software Update on your Mac

Note: Proceed Software Update may cause data loss if any errors occur during the update, you'd better back up your important files before update your Mac.

The problem still exists?

If your computer has already updated to the latest OS version, and the above ways fail to fix the kernel_task taking up high CPU problem, you have to reset your Mac or reinstall macOS to bring your Mac back to the normal state.


1. Can you stop kernel_task on Mac?

No. As kernel_task in Activity Monitor is a label that represents a series of activities that proceed since your Mac starts up, you can't quit it or stop it on Mac. You can check in Activity Monitor that the quit button for kernel_task is not available.

2. How to check CPU usage on Mac?

You should launch Activity Monitor (Under Finder > Application > Utilities). Select the CPU tab in the Activity Monitor window. Then, you'll see the CPU usage of every process.