[kbenson]

An article from 2013 means that it covers a change from at least Go version 1.2 (released 2013/12/01)) to 1.5 (released yesterday?). The performance section of each document talks about cases where it may go slower for faster in certain instance in every since release, including the one that was the change from C to Go for the compiler[2].

That said, I took the original statement about Go switching from Co to Go to indicate there's been major changes in the compiler, so it would be interesting to see more recent results, not that the change itself necessarily was responsible for major speed improvements, but they could very well have assumed the compiler change would have had a larger affect on the resulting binary depending on their understanding of the Go toolchain.

1: https://golang.org/doc/devel/release.html

2: https://golang.org/doc/go1.4#performance