When I open 1-2 tabs with sites that have many images (e-shop as an example) the CPU usage gets to 100% for Chrome/Opera/Firefox.

What I've tried:

  1. Reset Chrome to default settings
  2. Disabled all extensions
  3. Disabled "Use hardware acceleration" in Chrome settings
  4. Checked task manager in Chrome. Couldn't find anything except that a process called "Browser" takes all the CPU (100%+)
  5. Run malware check on MacOS with 2 different programs (avast and malwarebyte)
  6. Run diagnostics after restarting MacOS

Looks like any browser with webkit engine suddenly started consuming 100% CPU on any site which has at least some dynamic content, maybe images or some JS or something like that. Basically any site.

MacOS version: Big Sur 11.1

CPU: 2,5 GHz Quad-Core Intel Core i7

RAM: 16 GB

Graphics: Intel Iris Pro 1536 MB

  • 3
    If you disable hardware acceleration, then it's going to do it in software. With the CPU. Chrome does have a bit of a reputation for CPU/RAM usage. Have you tried Safari, or Vivaldi on the same sites for comparison?
    – benwiggy
    Commented Jan 7, 2021 at 18:28
  • When I enabled hardware acceleration, I still have 100%+ CPU, but the difference (at first glance) than when it's disabled, then Google Chrome Renderer takes most of CPU, while when it's enabled then Google Chrome (not renderer) takes 100%+ CPU. Hmmm. I'm going to try Safari, I just don't want to switch it it because I got used to chrome dev tools...
    – Victor
    Commented Jan 7, 2021 at 18:42
  • Same for Safari, now I got 100% on mtlcompilerservice process
    – Victor
    Commented Jan 7, 2021 at 18:46
  • If you're getting this for 'any site', then thats very wrong indeed. What happens if you run it in a new user account (as a test)?
    – benwiggy
    Commented Jan 7, 2021 at 18:48
  • Same. It behaves this way: when I open a new site, for 30-60 seconds I got high CPU usage, fans are working hard :) Then after some time, everything calms down. Tested on new user on Safari. It feels like it tries to render everything which is hard for OS for some reason
    – Victor
    Commented Jan 7, 2021 at 19:39

2 Answers 2


Setting two system preferences, reduce transparency and reduce motion, seem to have made a significant difference for me across several browsers:

  1. Open the  Apple menu, open ‘System Preferences’, then select the “Accessibility” preference panel
  2. Choose “Display” settings
  3. Check the boxes for “Reduce motion” and “Reduce transparency”
  4. Exit out of System Preferences

*Suggestion and steps from OSXDaily article; citation below.

Casual observation using Activity Monitor suggests browsers now use something like 30% of the CPU and memory (very casual method: I left the same moderately large number of windows and tabs open in Safari as I made the changes. Before: many fan cycles, much heat, many spinning beachballs, high % of resources in Activity Monitor. After: dramatic absence of all these telltales.

My guess at the reason: I noted a significant change in the appearance of the top bars of each window; browsers with lots of windows open may require a lot of resources just to calculate how all of them should appear with partial transparency.

I ran across this suggestion in a Jan 20, 2021 OSXDaily article macOS Big Sur Slow or Laggy? 8 Tips to Help Speed Up the Mac Again - credit to them for the solution.


Having the same issue. It's not very good even in Safari. I suspect the mtlcompilerservice, as I load pages I see a lot of instances of it in the Activity Monitor, consuming high CPU. TGPro shows high temperature of the CPU, 90+ celcius. Video playback heats up the device but loading pages and browsing around is the worst offender.

I have the 15" mid 2014 model with Iris Pro & Nvidia gt 750m. I thought the reason for overheating/fans-kicking-in-whenever-they-please was that Apple changed some things as to how GPUs work in Big Sur.

I'll try installing Big Sur to a separate volume, and if that doesn't help, I'll re-install macOS, starting from High Sierra and update here.

Idle temp: 54-60 C
Browsing: 70+ C

  • 1
    Tell me how it goes please, I gave up since I got no idea what to do. Tried everything I could. People usually say that chrome is CPU greedy, but come on, not for one site with few images. Definitely something with OS.
    – Victor
    Commented Jan 10, 2021 at 13:12

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