I have a single Raspberry Pi 3b as a local file/media server running Jellyfin. I’m also running BOINC and seeding torrents of various Linux distributions. External HDD for storage, plus a thumb drive for the local media and another for the torrents so it only has to spin up when someone’s actually using it.

It’s not super-fast by any means, but it’s fast enough to listen to music over my LAN, which is the main thing I need it to do quickly. Though eventually I plan on setting up a better NAS on something with faster I/O.