You can easily serve 10000 static requests/second per core on a modern server grade CPU over TLS with nginx, which is written in C. Slap node.js and express on

You can easily serve 10000 static requests/second per core on a modern server grade CPU over TLS with nginx, which is written in C. Slap node.js and express on top and you might dip to something like half of that. But the real win with using C (or rather, using direct syscalls) comes from how much of that throughput you can retain while serving dynamic content. At least on Linux, performantly serving a static file would have a syscall flow similar to the following: file -> splice -> pipe -> splice -> kTLS socket The performance increase comes from copying the file to the socket without any detouring of the data via userspace. This can easily be adapted for the case where you need to inject portions of that file with dynamically retrieved content, by using offset fields in the splice call from the file being served, and manually writing to the pipe to inject the dynamic content. You cannot easily replicate this construct in any other dynamic-content server framework I know of - you have to do it manually in C (or any language that allows you to directly invoke system calls).