I've been trying to upgrade from 10.10 to 10.11 for a while now, as the Android TV app keeps nagging me, and every attempt ended with impossibly long library scan times.
After some thorough investigation, it appeared that a Home Videos type collection causes unending scan (yet to be solved), but also that Jellyfin does a lot of writes to the config directory (either database or metadata or both). Mine's on spinning media part of a ZFS pool. I tried a few performance tuning options, such as testing the config dir with recordsize (similar to block size) of 4K, 8K, 64K, 128K and library scans fell from 30-40 minutes down to 8-13min with 4K-64K. The ZFS tuning wiki suggest 64K recordsize with LZ4 compression for SQLite workloads such as Jellyfin. That seems to work as well as 4K and 8K but likely is faster when reading thumbnails and such.
Note that upgrading to 12-rc3, which is supposed to speed up library scans did not improve scan times for me. Optimizing config/database write speed did. I cross-checked the culprit by experimenting with moving the config dir to NVMe and RAM. Both of those got the scan times down to 8-9 minutes compared to the optimized spinning media's 12-13.
So if you had upgraded (or about to) to 10.11 your library scans are (about to get) dog slow and your Jellyfin's config dir resides on spinning media, optimize its write performance for SQLite.
Outside the network you still have to open your server to allow plex cloud to access it and potentially tunnel your traffic through plex.tv if a direct connection doesn’t work. This happens automatically but it does happen
With Jellyfin you just have to supply your own relay, like Tailscale or wireguard, which does require more setup but is completely free, means that you can stop your media traffic from being funneled through services that harvest your data (which plex absolutely does), and doesn’t go to shit if plex.tv goes down
And that's the key, it happens automatically and it just works. With jellyfin you have to expose the web server to the internet, or point an app to something else exposed on the internet. With plex you don't. If you don't want to (or can't) a direct connection from your server to their servers, then their servers to your device is established. No VPNs, no reverse proxies, no port forwarding, nothing exposed to the rest of the internet.
What I'm praying for is for Jellyfin to add a tailscale like direct peer to peer system. They can skip the backup funneling traffic through their servers. But just have something that coordinates a direct connection with just basic NAT.
You can do the exact same thing with Plex, you just don't need to since automatic remote streaming is built in. In fact, the article's solution is literally Tailscale.
You can also bypass plex authentication on any ip range you choose, so if you add your local network and plex's auth service goes down, it's no big deal.
Yeah obviously, you can also use Tailscale to tunnel to whatever service you want (including just to the server itself). But if you’re bothering to override remote plex access with all this I don’t know why you wouldn’t just pick the option that doesn’t harvest your data and increasingly treat its customers as hostile