This solved the high CPU I’ve been experiencing for a couple of months. I don’t have any camera streams on my dashboards, but I eventually remembered my wall tablet has a camera which it uses to detect movement. Restarted Fully Kiosk from HA and my CPU has dropped from around 60-80% to 10-15% and RAM usage has dropped from 5 to 3GB 
Did you find any solution?
I tried to recreate the VM and restore the backup, but it didn’t work.
I don’t remember, but the issue is resolved. It might had to something with backups or changing the vm configuration. Sorry, I really would love to document what changed it.
In my case it was caused by Signal telling me that my number wasn’t registered (which wasn’t the case) and causing 100% CPU load. The easiest way to get a great overview is installing the Glances add-on. You can sort the add-ons by CPU usage (if it’s not an integration issue). This helped me identifying the Signal add-on. Restarting it solved the issue for me. Maybe the Glances add-on also helps some others here.
I recreated the VM and am monitoring it.
My problem started at the beginning of the year, but I don’t know exactly when or why, maybe a proxmox update.
The only clue I have is in the KVM process.
If the problem persists I will try to downgrade.