That first link is from 2009. A lot's changed since then, so I didn't read it.
And maybe I missed something in the second link, but Go showed very similar I/O performance to Elixir, while consuming a boatload less CPU doing it. That's what I'm after. Open to being told I missed something, though.
...shows pretty clearly how the CPU utilization grows linearly (ignoring some sawtooth) as the load increases, plateaus once the load remains constant, and then comes down linearly as the load decreases on the other end. Looks like a very clear mapping between work done and CPU load to me.