Baltic Vengeance 2 & 3 routers tested (i7-8700k + i9-9900k) using proxmox 6.3, tested both xl710 and 82599ES using multiqueue in proxmox and vitio drivers, performance is fine until about 2-3 gbps , I also tried rps off / on as well as multi-queue interface queues, all of the results are similar, completely disabled chr firewall no help.
Next I was going to try;
VMXNET3 instead of VIRTIO
OVS Bridges instead of Linux bridges
I've spent months googling and trying every performance optimization I can find anyone discuss...
My best results so far have been with PCI-passthrough but most of my nics won't work under pci-pass.