Another day, another "proof" that Ruby is slower than X, which surprises exactly no one.
The interesting thing here though is that considering the trivial amount of work to be done, Ruby shouldn't be that slow. I'd like to see the source code of the Ruby project to see if some simple improvements could have been made that aren't too invasive.
The spike in latency at around 15,000 requests could be explained by the garbage collector, which normally is put out-of-band. This makes me believe that he used a single-threaded, single-worker approach for Ruby. I don't know about the Go framework he used, but maybe it was multi-threaded (and not green-threads).
In fact, the ETA for Round 6 is next Thursday, June 20. If you can point out any tuning for us to put in place for the Ruby tests before June 17, we may be able to get pull requests accepted before we kick off the test runs.