Chrome Using High CPU When You Are Not Using It
Short answer
Press Shift+Esc for Chrome's task manager (Window menu on macOS), sort by CPU, and watch for thirty seconds without touching anything. Unlike memory, idle CPU always has one identifiable owner — usually a background tab with a timer, an extension service worker, or Chrome's preloading. Turn off Continue running background apps when Chrome is closed at chrome://settings/system if the usage persists after you quit.
On this page
Nothing is playing. No page is loading. You have not touched the keyboard in ten minutes, and the fan is running because Chrome is sitting at 25% CPU.
Memory and CPU behave completely differently here, and conflating them is the usual mistake. High memory with Chrome idle is normal and mostly a measurement artefact. High CPU with Chrome idle is never normal — CPU is only consumed by code that is executing, so there is always exactly one thing to find.
Find the owner
Press Shift+Esc on Windows or Linux. On macOS, use the Window menu → Task Manager, since there is no default shortcut. It also sits under the ⋮ menu → More tools → Task manager everywhere.
Click the CPU column to sort. Then stop touching anything for thirty seconds and watch which row stays high.
| What holds CPU | Usually means |
|---|---|
| A named tab | A script, animation, or a page polling a server |
| An extension | A service worker running on a timer |
| GPU process | Hardware acceleration misbehaving, or an animated page |
| Subframe (named ad domain) | An ad iframe running scripts |
| Browser process alone | Profile or sync problem, rare |
Select the row, click End process, and the usage stops immediately. That is the confirmation. The tab shows a crash page and reloads on click, so the cost of testing is nothing.
Once you have a name, the rest of this page is about what to do with it.
Background tabs that are exempt from throttling
Chrome aggressively limits what a tab can do when you cannot see it — timers get slowed to once per minute, rendering stops. Most tabs go genuinely quiet.
Four categories do not, deliberately:
- Audio or video playback. A paused YouTube tab is quiet; a playing one is not, and neither is a muted tab that is still playing.
- WebSocket connections. Chat apps, trading dashboards, live sports pages and collaborative documents hold an open connection and process messages as they arrive.
- Service workers. A web app can register one that wakes on push messages and sync events with no tab visible at all.
- Pages with a wake lock or active media session. Rarer, but they exist.
None of these is a bug. A chat app that stopped receiving messages when you switched tabs would be useless. The practical answer is to close the tabs you are not using and accept the ones you are.
The one thing worth looking for specifically: a tab that is costing CPU while doing nothing visible. Open it and check whether there is a video autoplaying below the fold or an animated advert in a sidebar. Ad-heavy news sites are the reliable offender here, and an ad blocker removes most of it.
Preloading
Chrome fetches, and in some configurations renders, pages it predicts you will open next. It genuinely makes browsing feel faster, and it costs CPU and bandwidth while you are doing nothing.
Open chrome://settings/performance and find the preloading setting. It offers
a standard option, an extended one that predicts more aggressively, and off.
Extended preloading on a metered connection or an older laptop is a poor trade. Standard is a reasonable default for most people. Turning it off entirely makes page loads measurably slower in exchange for lower idle activity, which is worth it on a thermally limited machine and not otherwise.
While you are on that page, Memory Saver is also worth having on. It discards tabs you have not touched, which stops them doing anything at all. What Memory Saver actually does covers how it decides and how to exempt the tabs you need kept live.
Extensions running in the background
Extensions register service workers that wake on timers and events, and they run whether or not you have a relevant tab open. A price tracker checking stock every minute, a sync tool polling an API, a coupon extension refreshing its database — all of it is CPU with no visible cause.
The task manager lists extensions by name with their own CPU figures, which
makes this one of the easier cases. If nothing obvious appears there, the
halving method at chrome://extensions finds it, and
how to find which Chrome extension is slowing you down
walks through that properly.
Chrome using CPU after you close it
This catches people out regularly. By default Chrome can keep background processes alive after the last window closes, so extensions and installed web apps keep receiving notifications. You will see a Chrome icon in the system tray.
Open chrome://settings/system and turn off Continue running background apps
when Google Chrome is closed. Then right-click the tray icon and choose
Exit to clear the current ones.
If Chrome processes persist after that, check whether you have installed web apps — anything you added with “Install” rather than bookmarked runs as its own window with its own process, and quitting the browser does not quit it.
The GPU process
A GPU process holding sustained CPU is a specific and informative symptom. The GPU process exists to hand rendering work to the graphics card; if it is burning CPU instead, the handover is failing and work is falling back to software.
Open chrome://gpu. Entries reading “Software only, hardware acceleration
unavailable” mean Chrome has blocklisted your driver.
The fix is a driver update direct from NVIDIA, AMD or Intel rather than through Windows Update. Toggling Settings → System → Use graphics acceleration when available off is a diagnostic, not a solution — leaving it off moves video decoding to the CPU, which costs several times more on every video you watch.
When it is not Chrome
Before rebuilding your browser, confirm the CPU is actually Chrome’s. Windows Task Manager and macOS Activity Monitor attribute per-process, and an antivirus scanning Chrome’s profile directory shows as the antivirus rather than as Chrome.
If the system is busy generally, finding what is using 100% CPU or disk is the right page, and why Windows feels slow covers the wider case. Chrome is frequently the victim rather than the cause, because it is the most demanding thing most people run and therefore the first thing that feels slow.
The sustained-load version of this problem, where Chrome is busy while you are actively using it, is covered separately in why Chrome is using so much CPU.
What to expect
The task manager identifies the owner within a minute in most cases, and the owner is usually a single tab you had forgotten was open.
Closing it, blocking the ads on it, or switching preloading down from extended takes idle usage back to low single digits on a healthy machine. That is what normal looks like: not zero, because Chrome does housekeeping, but not something you can hear.
If idle CPU stays high in a Guest window with no extensions and a single blank tab, the problem is Chrome’s interaction with the machine rather than anything you have open, and the GPU path is where to look.