[smt88]

A lot of the speed will be dependent on your ability to cache and your implementation of caching. After that, your speed will likely have more to do with your HTML/CSS/JS than your back end.

But, generally speaking, a compiled, static language like C# with .NET Core will be faster than Rails.

I don't have personal experience with them, but Rust, most JVM languages (e.g. Java, Scala, or Kotlin), and F# should also be faster.

Again, a lot depends on your specific code.