All of them have optimized and improved their speed since then.
In 2003, it was expected that web pages have a bit of a delay before loading. In 2016, it is not. Ruby has not yet adapted.
Additionally, computers got much faster and have many more cores, allowing for additional process concurrency. This is an argument for me to move to higher level, more abstract languages, not to race back to lower level languages because "they're fast". If anything, ruby/js/python aren't high level enough and could be slower but more productive. I'd choose that over raw performance for the vast majority of my needs.
Additionally, Rails benchmarks might show ~100 hits per second (that's 8,640,000 hits per day per process, do you actually get that much traffic?), but I can get thousands of hits per second running Sinatra. I still think Rails is plenty fast, but it's silly to blame a language for a framework.
Ruby has for years been a victim of FUD, opinions on it's performance that seem to have been derived from fuzzy stereotypes rather than actual information. I think that's what the author is frustrated about, because that's the one thing I'm pretty frustrated about too. I'll be the first person to abandon ruby when a better language comes out for my needs, but I've still never seen it.
However, threads will never help you in an IO-bound system (unless you own some kind of thousand-core CPU with an equal number of OS threads). Threads will simply block at the first waiting IO call until you eventually run out of threads. Node.js from the beginning was built for non-blocking IO, as are several Python frameworks (e.g. Twisted, or more recently, Tornado), thus the need for more than one thread of execution was typically unnecessary (again, provided the bottleneck was IO).
CPU in the web layer is not the bounding issue for most web apps.
Adding a vague "it's gotten faster" is not sufficient to mean that it's fast enough for 2016.
It may or may not have improved enough, but either way this argument does not prove that it has.
There are some technologies that were impractically slow in 2003 but have become 'fast enough' in 2016 either by improvements of tech or just by having more cpu/ram/gpu power - but not the other way around.