@Hello @kaidenshi @MaddieM4 You can control CPU frequency, check apmd manual. Or use obsdfreqd (i think it's called that). Probably still not as efficient as Linux, but you can get pretty close. I use the latter on laptops, when I'm out and about. obsdfreqd is in ports. You have to reconfigure apmd to disable some of its automation; check both manuals. Or just disable apmd when using obsdfreqd.
Also, I'll update librewolf soon. Got other work on at the moment. But will update the port after 7.9