Chrome High CPU Usage on Mac: Find the Tab, Extension or Service Behind It

Chrome high CPU usage almost always has one cause you can name: a single tab, extension or background service running code nonstop. The fans spin up, the Mac gets warm, and Activity Monitor shows a wall of processes called "Google Chrome Helper" without saying which site is which.

This guide shows how to find the exact culprit in under a minute, fix it in the right order, and deal with the newest offender people report on Reddit this year: Chrome's On-Device Model Service. We ran the tests on one of our own Macs, so the numbers below are measured, not guessed.

The short answer#

• Open Chrome's Task Manager (Window, then Task Manager on a Mac) and sort by CPU.
• End the top process. It is usually one tab or extension.
• Test extensions if the spike returns.
• Stop the On-Device Model Service if that is the name at the top.

Why is Chrome using so much CPU?#

Chrome splits its work into many processes. Each website, extension and service runs in its own, so one bad page cannot crash the rest. The flip side: one bad page can still keep a CPU core busy on its own.

The common causes, from most to least likely:

1. One busy tab. A web app polling for updates, an animated ad, a page stuck in a loop, or a site that keeps reloading.
2. An extension. Ad blockers, shopping helpers and tab managers run on every page you open. One with a bug runs everywhere.
3. Video and video calls. Decoding high-resolution video and encoding your camera are real work, especially without graphics acceleration.
4. Built-in AI. The On-Device Model Service runs Chrome's local AI model. Users report it pinning the CPU even with AI features they never use.
5. Many tabs at once. Each tab costs a little. After a restart, Chrome reloads them all together.

On r/chrome, a June 2026 thread describes CPU at 70-80% with only 5-10 tabs open and nothing happening, dropping to normal only when Chrome closes. That pattern, high CPU while idle, almost always points to cause 1, 2 or 4.

How do I see what is using CPU in Chrome?#

Activity Monitor cannot tell you. On our Mac, with Chrome 155, it listed the page processes as Google Chrome Helper (Aperitif Renderer), with no site name, ten of them. Chrome's own Task Manager shows the same processes with names:

1. In Chrome, open the Window menu in the Mac menu bar and choose Task Manager. On Windows, press Shift+Esc. On any system, the three-dot menu, then More tools, then Task manager works too.
2. Click the CPU column header to sort the heaviest process to the top.
3. Read the name: Tab: followed by the site, Extension: followed by its name, or a service such as GPU Process, Network Service or On-Device Model Service.

Watch it for 10-20 seconds. A process that spikes and drops is normal work. One that stays high while you do nothing is your culprit.

What we measured on a Mac#

Tested on a MacBook Pro (M1 Pro), macOS 26.3, Chrome 155, running on battery, October 20, 2026.

To see what "one bad tab" looks like, we started Chrome with an empty test profile (so no extensions or old tabs) and measured each Chrome process with macOS's top, three samples each:

One misbehaving tab used about 20 times more CPU than our whole everyday Chrome session with 27 processes. Without that tab, the same clean Chrome sat at 0%. This is why the fix below starts with Task Manager instead of "clear your cache" or "reinstall Chrome".

We also tried to measure a heavy animation with graphics acceleration on and off, but macOS paused the animation whenever the test window was covered by other windows, so the numbers were not trustworthy. We left them out.

How to fix Chrome high CPU usage, in order#

Start with the step that costs nothing and solves most cases. Move down only if the spike comes back.

1. End the process at the top#

1. In Task Manager, click the process with the highest CPU.
2. Click End process.

If it was a tab, that tab shows a "page crashed" message; reload it when you need it. If CPU drops and stays down, you are done. If the same site does it every time, it is that site, not your Mac. Keep it in its own window and close it when you are not using it.

If a site keeps getting stuck after a deploy or a bad update, its saved data can be the trigger. Clearing just that site's data fixes it without signing you out anywhere else. Clear cache for one site shows how.

2. Find the extension that keeps coming back#

If an Extension: line keeps returning to the top:

1. Paste chrome://extensions into the address bar.
2. Turn all extensions off with their switches.
3. Turn them back on one at a time, using Chrome normally for a few minutes after each.
4. When the CPU spike returns, the last one you turned on is the cause. Remove it or look for an alternative.

Extensions you do not remember installing are worth removing anyway. They run on every page.

3. Turn graphics acceleration on#

Video, maps and animated pages run on the GPU when Chrome can use it. Without it, the CPU does that work.

1. Open Settings, then System.
2. Make sure Use graphics acceleration when available is on.
3. Click Relaunch.

Some guides suggest turning this off to fix high CPU. That only helps when a graphics driver bug is the cause, which is rare on a Mac. Try it the other way round only if a video glitches or flickers.

4. Let Chrome rest background tabs#

Two built-in settings cut background work, both under Settings, then Performance:

• Memory Saver puts tabs you have not used for a while to sleep. Google's help page notes that tabs playing audio or video, sharing your screen or downloading are not put to sleep.
• Energy Saver reduces background tasks and stops eligible CPU-heavy background tabs, according to Google. It turns on when your laptop is unplugged or the battery is low, not while plugged in.

Neither helps with the tab you are looking at. They stop the 30 tabs you are not looking at from adding up. For the memory side of this, see Chrome using too much memory.

5. Relaunch and update#

Type chrome://settings/help. Chrome checks for an update and offers Relaunch. A relaunch alone clears stuck processes, and some CPU bugs are fixed in point releases. Chrome reopens your tabs after the relaunch.

6. Reset settings, last#

If nothing above helps, Settings, then Reset settings, then Restore settings to their original defaults turns off all extensions and resets site settings. It also clears cookies, so you will sign in again. Treat it as the last step.

What is the On-Device Model Service, and why is it using 100% CPU?#

The On-Device Model Service is the Chrome process that runs Gemini Nano, the small AI model Chrome keeps on your computer for built-in AI features such as writing help and summaries. Google's developer guide lists its requirements: a GPU with more than 4 GB of video memory or a CPU setup with 16 GB of RAM and 4 cores, plus 22 GB of free disk space.

In June 2026 a Windows user on r/chrome reported the service pinning the CPU at 100% about once a week on two computers, loud enough that the fans "kick off like a jet engine", even though they had AI features turned off. The fix they used was ending it in Task Manager each time.

On our Mac, the model was on disk, a 4.27 GB file called weights.bin in the OptGuideOnDeviceModel folder, labeled v3Nano. The service itself was not running during our tests. It starts when a feature or a website asks Chrome for the model.

If it shows up at the top of Task Manager:

1. End it now: select On-Device Model Service in Task Manager and click End process. Chrome keeps working; only AI features stop until it restarts.
2. Check what it is doing: open chrome://on-device-internals to see the model's status.
3. Turn it off for good if you do not use Chrome's AI features: Settings, then System, then switch off On-device AI. PCWorld reports this deletes the model file and stops Chrome from downloading it again. The switch can be missing on computers your work or school manages.

Turning it off also frees about 4 GB of disk space. Our breakdown of Chrome taking up too much space shows where else Chrome keeps large files.

When high CPU is normal#

Not every spike is a problem. These are expected and short:

• Opening or reloading a heavy page. A few seconds at high CPU, then it settles.
• Video calls. Encoding your camera and decoding everyone else's is steady work for the whole call.
• 4K or 60 fps video. Higher still if graphics acceleration is off.
• Starting Chrome with many tabs. Each tab loads at once, then goes quiet.

The test is simple: if CPU stays high for minutes while you are not doing anything, something is wrong. If it drops when the page finishes, it is Chrome doing its job.

Keep it from coming back#

A few habits stop most repeat cases:

• Glance at Task Manager when the fans start, before closing everything. Ten seconds tells you the real cause.
• Keep extensions few. Each one you remove is code that no longer runs on every page.
• Close web apps you are done with. Mail, chat and dashboards keep working in the background.
• Relaunch Chrome every few days so updates install and stuck processes clear.

On a Mac, Activity Monitor's long list of Chrome helpers is hard to read. If you want to see how much memory Chrome uses as a whole, RAM Rescue, a free Mac app we make, groups all of Chrome's helpers into one card with a Quit button. It tracks memory, not CPU, so use Chrome's Task Manager for the CPU side.

If Chrome feels slow even when CPU is low, the cause is usually elsewhere. Why is Chrome so slow goes through the other suspects.