Please do not take offense or feel like you were being attacked somehow. @jtp10181 , @672southmain @bertabcd1234 and @danabw are some of the most helpful people in the community and all have helped me immensely at times. The post @jtp10181 linked to is fairly new but it is tailored towards self help, and if that fails getting your problem figured out quickly and get you back up and running! Please remember these people are not employees of Hubitat, they are users just like you and me who give their time and experience to help other where they are able.
My immediate thought is that the only real time I've had that issue with my C8 was when the memory got too low. There is a great community driver to help monitor hub health written by @thebearmay, it's called Hub Information Driver V3. Depending how deep you want to go down that rabbit hole you could also Use HE with with InfluxDB, Grafana, with InfluxDB Logger which would provide some very useful graphs to monitor your systems.
Like you I am mostly Z Wave, more devices, but still not a large system. The other time I have seen that (on earlier hubs) was with a particularly chatty device. That device brought my mesh to it's knees in no time. I finally had to remove it and wait (a couple years) until a firmware update came out to fix the problem. In that instance @jtp10181 was of great help!
Hopefully all of this will help get you up and running and keep everything on track!
