When building Edera (product from article), I also had the added problem of the virtual networking gap where I was bridging a 10Gbit NIC over a virtual interface, and I had weird performance bouncing between 3Gbit and the full 10Gbit. Luckily I had built networking drivers before and knew the complexities of it, and managed to profile it down to the virtual interface getting worst-case NUMA occasionally.

The part 2 is going to cover how we actually solved it, which involves every part of the system having knowledge. It's so easy to ignore but it has a massive impact on perf.