I encoded 1250GB~ of Star Trek: The Next Generation Blu Ray's to 355GB of H.265/HEVC video, and I feel the result speaks for itself https://i.imgur.com/VklppOK.jpg
FWIW. Running the file through an i7-4790 would take roughly 4 1/2 hours
A GTX 1000 series does it in 4 minutes
Gold standard for H.264 quality/encode time/bitrate is still x264 medium / slow.
For H.265, the situation is much different. x265 is far from as mature as x264 and frankly the licensing is such a mess that it looks like H.265 might actually lose the war of next generation codec. Instead VP9 -> AV1 seems to be the industry’s codec of choice with adaption from Google, Twitch and Facebook. Also note Apple is back on the AV1 page.
Fast forward 10 years and basically every single laptop has hardware accelerated H.264 encoding through Intel's QuickSync FFHW and desktops have it through Nvidia. On top of that the software encoder (x264) is so fast that it's possible to do it in realtime on a CPU.
There is a fair chance that VP9 will see the exact same pattern here. Today CPU encoding is unfeasible, as you've noticed. However Intel is releasing VP9 encoding on their QuickSync encoder with newer CPU's and Nvidia will from my guess have it either 1 or 2 GPU generations from now. Same goes for AV1 here.
It's also interesting too think that the age of these aggressive improvements in CPU speed we've had over the past 14 years (from 2005) might come to an end, where efficiency instead comes from specialised hardware, such as fixed function hardware doing encoding on the chips, as NVENC/QuickSync does today. I don't know if realtime AV1 encoding will be feasible on a consumer grade CPU within the next 10 years, but i sure know it's hardware counterpart will be.
Of coz that is if you care about quality and retaining film grain that sort of things. Otherwise Hardware encoder from Nvidia is pretty good ( No idea about Radeon, but it seems Intel still doesn't care about encoding quality, they only care about speed. )
There's a very visible quality drop when streaming with NVENC, but that's realtime.