[throwaway270925]

> but 10x slower is too weird to be correct.

It is though. Had the same experience, dog slow transfers in FreeBSD on brandnew servers with 10/25G+ cards, hovering at 1-2G speeds. Only switching to Linux helped, and now easily saturates the links.

> speed limit imposed by a 1 Gb/s Ethernet link

FreeBSD might be slow, but its not that slow that it cant saturate a 1G link ;)