Interesting, but now I'm even more confused. How can we possibly explain that a (go client -> go server) (which are in separate go processes) performs far worse than (go -> scala server), given that the go server seems to be better when using the scala client?

The comments on the article page have a different report which doesn't suffer from this implausibility:

go server + go client 22.02125152

scala server + scala client 3.469

go server + scala client 3.562

scala server + go client 4.766823392