If you're moving those kind of speeds you're probably not doing packet filtering in software.

But you may be using Unix-y software to manage the interfaces and do offload programming:

* https://en.wikipedia.org/wiki/Vector_Packet_Processing

* https://www.youtube.com/watch?v=ptm9h-Lf0gg ("VPP: A 1Tbps+ router with a single IPv4 address")

* https://en.wikipedia.org/wiki/Cumulus_Networks

I use VPP and handle bonded speeds of 200gbit. Not that far fetched to also do this at 1000gbit.

Probably? But if you are then you’re certainly not using OpenBSD.