You are making an awful lot of assumptions without having enough info about this particular application.
Quote myself "but you solve a specific problem, as your example shows."
So I have to assume your choice of technology for your problem was the correct one & the stats you supply seems to backup such claim.
However you also implying a bigger claim that C++, or something similar, is preferable in web development, where you mostly do string handling, is not something I can agree with.
I was contracting with a decent size org a while ago and they had tons of web applications, some of them very giant. The total size of their code is insane and it is all PHP and Python on a server size. I was personally dealing with their application that had more than 5000 source code files. There was a lot of logic in there I would say, not just ReadString / TransformString / WriteString. That particular application would've definitely benefited from faster language.
I understand that in many cases most of the heavy lifting is done with the libs created in C/CPP and the rest is just a thin glue but I do not really know the real world stats on a subject.
So you can be right or not or the truth is somewhere in a middle.