It was auto-translated from C to Go. This means, they replaced well-written C code with badly (unoptimized, nonidiomatic) Go code. The reason was, to guarantee

It was auto-translated from C to Go. This means, they replaced well-written C code with badly (unoptimized, nonidiomatic) Go code. The reason was, to guarantee that the initial Go based version was identical to the proven C version. With the releases subsequent to 1.5 the cleanup and enhancement process of the Go version started and now it shows nice results. I think its one really great feature of Go, that the whole build/runtime infrastructure is written in Go itself. So, everyone who is fluent in Go can easily read and possible enhance the infrastructure.