Yea, it's amazing how quickly videos stream from most services.
If your Plex videos are taking a while to start, might be an issue with your client or server setup. Are the disk drives sleeping so they have to spin up, are they slow for some other reason, etc. My storage is all on spinning disk on 8+ year old hardware and I don't have any issues, except with certain slow clients.
the slowdown is with 4k movies - all codec (audio/video) match so no transcoding, plex runs in a vm with 4 typically idle cpu's allocated, and disks are cached with ssd's on a synology.
still the slowest of the players I watch. you can use infuse, and often times it is much faster than the plex client against the same server.
If your Plex videos are taking a while to start, might be an issue with your client or server setup. Are the disk drives sleeping so they have to spin up, are they slow for some other reason, etc. My storage is all on spinning disk on 8+ year old hardware and I don't have any issues, except with certain slow clients.