At some point Mozilla starts consuming CPU very intensive.
At some (random) point Firefox starts comsuming CPU very intensive. I can't detect any circumstances why and when it happens. Just after some period of using it freezes for a couple of second and then becomes slow and starts using CPU. I reload it and everything works fine again.
I use recommended perfomance settings and Firefox Developer 86.0b9 (64-bit). Please let me know if I can provide any additional information to help to solve the issue.