Firefox and Chromium running on Windows 7 by e3kskoy7wqk.

[ED_Sln]

8 hours ago, Slavich said:

The developer's browser from the adjacent topic does not have such oddities.

The version there is significantly lower. Even between 2-3 versions, the load can be higher. Check the CPU load in Task Manager. If it is close to 100%, install the h264ify extension or https://vorapis.pages.dev/#/home/download

To disable the message about unsupported OS, do the following: 

reg add "HKLM\Software\Policies\Chromium" /v SuppressUnsupportedOSWarning /t REG_DWORD /d 1 /f