If you scale from 1000MBit to 10Mbit and everything works, doesn't Clock/Interrupt seem like a more likely cause of the problems people are seeing than power? If you change your CPU clock governor to performance and that affects your Ethernet performance, doesn't that suggest the Ethernet is on a governed clock? Are we using the right clock for the job? Is the clock configured correctly?
I will note on Gigabit settings an 80% packet loss on the local network at a packet rate of 1/s which is enough to reduce any TCP to a standstill.
I will note on Gigabit settings an 80% packet loss on the local network at a packet rate of 1/s which is enough to reduce any TCP to a standstill.