Transcoding is always the bottleneck with these, right?

720p is good enough for me so... can we all just use that and give up on transcoding?

Most even remotely modern Intel chips can transcode a few 4K streams without breaking a sweat due to the integrated graphics/QuickSync.

I purchased one of those $150 tiny machines on Amazon specifically for the Intel integrated graphics so my Plex server can transcode easily. All media is another one of my servers, shared via NFS.

If you wanted to skip a step, you could find a copy someone else has already transcoded for the physical media in your possession. I'm not suggesting anything, just pointing out what one could do.

You generally don't need to do any transcoding if you're only streaming to devices on your local network. I have an old 1060 set up for my Jellyfin server but it pretty much never gets used.

Even cheap old desktop intel i5's are likely to have QuickSync, which can be pretty effective at transcoding video.