But even with idiomatic code the performance is quite good - the JITs are very high quality.

Node's still relatively slow for those workloads.

https://www.techempower.com/benchmarks/#section=data-r18&hw=...

See how far down in each section you have to scroll to find node, even for workloads that are purely "accept a request and respond with a static string". You'll see lots of Java and Go on your way down.

And most services will have far more compute than just shoving bytes in between services. There's request parsing, response encoding, usually at least a tiny bit of data manipulation.