I can't think of a reason for still images to use that kind of CPU. Possibly some animated images that render as videos could do it??

I notice in your add-ons list that "ImageAssistant Batch Image Downloader" is installed but disabled. Usually, if an add-on is disabled we can rule it out as an issue, but if you can live without it for a bit, maybe completely uninstall it and see whether that makes any difference.

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or if userChrome.css/userContent.css is causing the problem.

• switch to the Default System theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click "Refresh Firefox" in the Troubleshoot Mode start window

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

I can't think of a reason for still images to use that kind of CPU. Possibly some animated images that render as videos could do it?? I notice in your add-ons list that "ImageAssistant Batch Image Downloader" is installed but disabled. Usually, if an add-on is disabled we can rule it out as an issue, but if you can live without it for a bit, maybe completely uninstall it and see whether that makes any difference.

Thank you for replaying, I removed it and cleared cookies and the problem consists . Both in Yandex and Google

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or if userChrome.css/userContent.css is causing the problem.

• switch to the Default System theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click "Refresh Firefox" in the Troubleshoot Mode start window

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Firefox in Troubleshoot Mode - No fix . hardware acceleration was true now false not fix . switch to the Default System theme - It was on system theme - auto -- Changed to dark still same problem .

do NOT click "Refresh Firefox" in the Troubleshoot Mode start window - i Clicked open

What are userChrome.css/userContent.css ? and how to i edit delete them ?

So i checked and userChrome.css/userContent.css are to editing firefox internals which i never touched .

• • Not related**

I saw jscher2000 - POST https://www.userchrome.org/firefox-89-styling-proton-ui.html Nice man.

Another picture if is helps .