Tacking onto this comment as another thumbs up for vaultwarden. "incredibly reliable" is exactly the way to describe it, in the world of tech headaches the password manager is the last thing you want to be worrying about and I can say with confidence that vaultwarden is a reliable well-oiled machine.
Backups are also fairly easy so if need be a DR can be done (and automated) with very little hassle. The vaultwarden backend does depend upon the bitwarden apps for client devices but also features it's own web UI.
Now a days the major performance difference between languages is memory handling and allocation.
Microsoft has been making major moves in how c# gets compiled (AOT/JIT/Native). This is a concurrent effort to cross-platform support.
In doing going so they've minimized performance differences with other languages. The only thing they've yet to completely tackle is memory handling, so in reality, while it might not seem like it at first, your question is asking about that subject. Also some small tidbits with property accessors that the other comments have noted. To my knowledge these will be optimized away soon.
The GC is responsible for allocation and destruction.
>And I had a heck of a time getting a config that allows each contained thing to see the others
Use a utility container to learn some of the network/options of docker. The network-multitool[1] container is a good one I use.
So for example, create a few containers in a manifests/compose file with different network settings and try pinging, telneting, etc from one container to another.
This container can also be used to help debug workload containers that are having connectivity issues. If you need more tooling just create an image with this container as a base.
Backups are also fairly easy so if need be a DR can be done (and automated) with very little hassle. The vaultwarden backend does depend upon the bitwarden apps for client devices but also features it's own web UI.