After BIOS update and replacing the CPU (9900k stepping R0) and updating the drivers for the video card from nVidia (without which it refused to work), this started like this. There were no other changes in the system at all. In addition to the impossibility to close the application normally and the full load of one processor core, as can be seen from the Task Manager, there are no other problems, everything works as usual. I've tried disabling all extensions (there are only a few of them). I also turned off hardware acceleration. I didn't reset the browser settings, because so far I really don't want to do this unless absolutely necessary. Also, my browser sent a dozen reports with logs.

I am trying to understand why this is happening and change the settings that I made changes to (as far as I remember), but nothing seems to help at the moment.