The Roon forum is full of similar reports of instability, many from me. Of course they attract the "Roon runs flawlessly for me" posts as well. The equivalent of "I can eat onions so why do they bother your stomach?"
One thing that those with "flawless Roon" seem not to address is that there are variables beyond local hardware and network to consider. The nature of one's library has a lot to say about how Roon acts and when it sucks up all the system resources and grinds itself to instability. And I firmly believe that local Roon relies very heavily on the Roon network and that various forms of instability and slowness originate from the SAAS part, or at least it's an interaction with local.
The real problem with Roon is that there isn't really anything else like it. Once you've configured your gear for it, it's hard to turn back.
I've been able to mitigate my issues with Roon significantly by using a very powerful machine as a Roon core, in an area where fan noise doesn't matter, running Ubuntu server without anything else on it, with all locally stored files on a drive right in the machine, with at least 32GB of RAM. Then use very clean and quiet endpoints via wired network.
Roon still does goofy stuff, including going silent at the end of every few songs while reflecting that it is still playing, playing the same artist every other song in Radio, and occasionally being very slow. But at least with Ubuntu you can see system resource usage and restart or reboot when necessary.
With some of the more common issues, it looks like Roon may be admitting they are a hard fix and is providing some tools to mitigate these problems as well. For example, it looks like they are testing a version that allows metadata updates to be scheduled for off hours. Now, if Roon would just allow a restart from any remote!
For the work it would take to migrate a heavily manicured library to a different solution, and the fact it wouldn't be as good, I would recommend trying to mitigate Roon's faults with substantially updated hardware. Also clean your library of unidentified albums if you can.

