I think it is one of those things where even if it is "fast enough" in most cases, why not just use one of the readily available faster options anyway? It's not

I think it is one of those things where even if it is "fast enough" in most cases, why not just use one of the readily available faster options anyway? It's not like setting up FastCGI is onerous. Apache/Nginx front-ends to a FastCGI process are as straightforward as you could ever want and the vast majority of languages you might use in this configuration have decades old battle-tested libraries and tooling. In fact, I drastically prefer having no front-end requirement. Even if node is "slow" compared to some C FastCGI benchmark, I like the operational simplicity of deploying code onto some stripped down Linux with minimal explicit dependencies. Go offering a single binary is even more attractive. I was always frustrated running Apache/Nginx, then maybe some process manager like PPM, fighting with the configuration across a bunch of different formats. While I admit that modern container based orchestration can be overly-complex, it doesn't leave me nostalgic for the days of CGI.