Piracy: ꜱᴀɪʟ ᴛʜᴇ ʜɪɢʜ ꜱᴇᴀꜱ

This is probably the best answer you will get OP ! I have done some encode (BD -> SVT-AV1) and everything FBJimmy said is everything I have gathered through my search on how to get the best quality/speed encode without loosing to much of fine details.

This won't make you happy if what you want is to use GPU encoding, cauz this is for on the fly encoding (streaming via twitch, Youtube, whatever...). It seems a nice idea to do GPU encoding but CPU software encoding is way more efficient than GPU.

It seems You aren't looking for quality video encoding, but more speedy encoding? If that's the case, yeah GPU encoding seems the best idea here. But can't help sorry...

Most of the encode I have done with ffmpeg on AV1 got arround 20fps ? Yes it's slow, however I get near "lossless" quality with an acceptable file size to serve over Jellyfin. Also, I never heard someone mention that 80-90% CPU utilization is bad for your CPU if your temps are all right (over 80° seems a bit alarming). Sure if you're doing video encoding every day, your CPU will suffer offer time, I mean that's practically what they are build for... Processing information ! And like everything, the more you use it, the more it wears out (the same goes for your GPU...)

But I can understand your determination and hope you will find your way arround. I'm also stubborn when I want something to work the way I want.