I really can't imagine that this benchmark is relevant anymore. Haven't Go, D, and Erlang had major changes since then? E.g., Go is now compiled by a compiler written in Go.
I'm planning on updating it this year once I finally find the time to learn Rust. Developing an MQTT broker has become my go-to task for learning new languages.
It's clearly optimized for latency over throughput. For one, it is single threaded -- unlike the Erlang, Go and, I believe D (vibe.d) implementations. Also, I don't know exactly how the benchmark was performed, but Java takes time to warm up (otherwise you're testing a completely different implementation of Java, which is only used at startup time).
I've found that for long-running server-side apps, Java is very hard to beat in terms of performance, especially relative to the effort spent. I also think it's a nicer language than Go (I also prefer it over C++ and D).
How Go is compiled isn't as relevant to its performance as much as what Go is compiled into, which hasn't changed all that much as far as I know. The GC improvements might help with latency though.
The translation of the compiler from C to Go was a mostly mechanical transformation, specifically to prevent any changes in the resulting compiled programs. Go compilation is getting better all the time, but the switch itself did not change the resulting programs.
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.
It's still hard to take any benchmark seriously when given the quote:
> Mosquitto was compiled with gcc 4.8.2, the Go implementation was executed with go run, the D implementation was compiled with dmd 2.0.64.2 and the Erlang version I’m not sure.
The "I'm not sure" speaks for itself, but go run also includes both compilation time and execution time and they're comparing it against just the execution times of the other languages. That's not exactly an apples to apples comparison.
I didn't write the Erlang version, don't know Erlang nor have any idea how it's built. The curious can always check the code out.
I don't know why you think that start-up time has an effect on the benchmarks. It doesn't matter how long the brokers take to start, once they did the measurements were done. `go run` doesn't change a thing.