Maybe I just haven't hit the right combination of great nic and questionable CPU, but I've seen segmentation offloading result in weird/bad things on the wire, and when I turn it off, I don't see any difference in CPU, so I don't see the point of ever having it on. Specifically for transmit offloading, with dual xeon 2690s, doing https serving via 2x 10gbps nics.

Additionally, I've seen the effects of weird bugs with receive offloading in Linux routers as well: If packets get combined before forwarding, they can be dropped because of the mtu on the next hop interface, so the performance enhancement is actually decreasing performance (and since it's a middle box, I can't do anything except hope my packets don't arrive close enough in time to get aggregated)