When I use OpenSpeedTest to to test to another VM, it doesn’t read or write from the HDD, and it doesn’t leave the Proxmox NIC. It’s all direct from one VM to another. The only limitations are CPU are perhaps RAM. Network cables wouldn’t have any effect on this.
I’m using VirtIO (paravirtualized) for the NICs on all my VMs. Are there other paravirtualization options I need to be looking into?
What do you mean specifically? If I’m already testing between two VMs, doesn’t that already isolate any issues to Proxmox? Is there another performance metric you think I should be looking at?