I have around 6 cameras, mostly 1080p, and about 8 GB RAM and 3 cores on the VM (plus Coral USB and Intel VAAPI). CPU usage is about 30 - 70% depending on how much activity there is. I also have other VMs on the machine running container services and misc stuff.

There are some camera stability issues which are probably WiFi related (2.4 GHz is overloaded) and Frigate also has its own issues (e.g. with detecting static objects as moving) but generally I’m happy with it. If I optimize my setup some more I could probably get it to a < 50% utilization.