I bet it’s performing a full library update of metadata. It’s happened to me it brings the server to its knees when it kicks in for no reason. I created a ticket for it. I checked my logs after it was back to normal and it showed it was a full metadata update happening. It disconnected all remotes and stopped music playing. I could connect via other means to the pc so not my network just Roon maxing out one CPU.
Support seem to think it’s down to Roon tags. Do either of you use Roons tags a lot?
Here is my ticket