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.
Do you have any proof that it's not secure?
The developers of jellyfin themselves say it’s not.
I think you've fundamentally misunderstood some of their communication.
There's the issue I described earlier where it is possible to stream files unauthenticated if you know the folder structure on the video. The devs have responded that they won't fix this. Outside of streaming content, there's no other access through this mean. https://github.com/jellyfin/jellyfin/issues/1501
Then there's the release of 10.11.7 that fixed a number of security issues. https://github.com/jellyfin/jellyfin/releases/tag/v10.11.7 with no major security issues since then. And all the issues were privilagr escalation for a normal user account on jellyfin. So the attacker would already needed to have an account on your server, and only the data that jellyfin could see was at risk, nothing escaped contagion so to say.
They also officially support a reverse proxy set up: https://jellyfin.org/docs/general/post-install/networking/reverse-proxy/.
I have no idea where you've got the idea where they themselves claim it's unsecure to open it to the internet. Of course there's always a risk associated with exposing something, but jellyfin doesn't pose any larger risk than anything else you might publish.
Accessing files unauthenticated……the devs explicitly say they won’t fix it….. and you think that’s not a huge security hole? Software with something like that marked as “won’t fix” is a giant no-no for me. If they’re ok with that, their software should be nowhere near an internet connection.
The person with a fundamental misunderstanding is you.
I do agree it's an odd choice not to fix it, and I do wish they would. But for now it's a risk I'm fine with taking. If my server gets DOSd in the future from multiple unauthenticated streams I sure will be a grumpy git and complain to them, but in the mean time uuh... sharing is caring? 😅
Just wait til movie studios start fishing for people hosting their movies illegally. With how everyone standardises their media structure and file names these days, finding people hosting your movie would be a cinch.