Well, the Ethernet interface is PCI-E, so there's a good chance it would be efficient.
One thing to keep in mind is that USB 3.0 is a completely different independent controller from 2.0. So, just because USB 2.0 sucks doesn't necessarily mean 3.0 does.
It's just unfortunate because you would expect 2.0 to be well optimized by now. I assume the kernel driver must be using the CPU to shovel data from the USB 2.0 controller rather than DMA.
One thing to keep in mind is that USB 3.0 is a completely different independent controller from 2.0. So, just because USB 2.0 sucks doesn't necessarily mean 3.0 does.
It's just unfortunate because you would expect 2.0 to be well optimized by now. I assume the kernel driver must be using the CPU to shovel data from the USB 2.0 controller rather than DMA.