Thanks again!
Meanwhile, I stepped in a bit deeper. I queried ChatGPT and got a very detailed technical elaboration. And at the same time I found also the following guide: "OPNsense Performance Tuning for Multi-Gigabit Internet". Most arguments in this guide are similar to those in the elaboration from ChatGPT. Additionally, ChatGPT also pointed out the aspect of hugepages on the proxmox host, but also on the VMs configuration, but I was unable to set it in OPNsense with hw.pagesizes = 1073741824 neither as OPNsense tunables in the GUI nor at the /boat/loader.conf or loader.conf.local level. However, with those tunings from ChatGPT and particularly from the guide, I was able to raise overall network speed by a factor of 3 to 4 (depending on how many threads are tested by iperf3 — not across the OPNSense instance) from as little as 0.9 to 1.2 Gbps to 2.5 to 4.2 Gbps (also with ookla speedtest for Internet connection). Sure, this corresponds not nearly to the available 10Gbps (internal and external), but this is for the moment better than the previous situation. Although it remains somewhat disappointing (considering the time and effort to get the system(s) tuned).
best
P.S. In OPNsense hw.vtnet.csum_disable: 1 is set by default at boot-time on a global level. But strangely enough, only setting on every single interface "Overwrite global settings:yes > Hardware CRC:Disable hardware checksum offload:yes) gives a speed increase of 10%.
Meanwhile, I stepped in a bit deeper. I queried ChatGPT and got a very detailed technical elaboration. And at the same time I found also the following guide: "OPNsense Performance Tuning for Multi-Gigabit Internet". Most arguments in this guide are similar to those in the elaboration from ChatGPT. Additionally, ChatGPT also pointed out the aspect of hugepages on the proxmox host, but also on the VMs configuration, but I was unable to set it in OPNsense with hw.pagesizes = 1073741824 neither as OPNsense tunables in the GUI nor at the /boat/loader.conf or loader.conf.local level. However, with those tunings from ChatGPT and particularly from the guide, I was able to raise overall network speed by a factor of 3 to 4 (depending on how many threads are tested by iperf3 — not across the OPNSense instance) from as little as 0.9 to 1.2 Gbps to 2.5 to 4.2 Gbps (also with ookla speedtest for Internet connection). Sure, this corresponds not nearly to the available 10Gbps (internal and external), but this is for the moment better than the previous situation. Although it remains somewhat disappointing (considering the time and effort to get the system(s) tuned).
best
P.S. In OPNsense hw.vtnet.csum_disable: 1 is set by default at boot-time on a global level. But strangely enough, only setting on every single interface "Overwrite global settings:yes > Hardware CRC:Disable hardware checksum offload:yes) gives a speed increase of 10%.