[flavio81]

>but you need to tail the code for the hardware, which is niche

Not really.

You just need to declare the data types (Common Lisp supports type declarations) and tell the compiler you want the code to be fast, which reads just like that:

(declare (optimize (speed 3)))

You also need to use the same tactics you would use in C to gain speed: Use arrays instead of lists, use threads. All of this is easily doable in Lisp and IMO while it takes more effort than writing typical Lisp code, it is easier than using C and the end result is more elegant and debuggable.

This is not hardware dependent, mind you.

[xuejie]

This is really depending on your view, but the moment you step outside of lists and use arrays, you are keeping modern CPU architecture in mind. And all of a sudden all those wonder car/cdr/cons concepts as well as things built upon it no longer holds, which, again depending on the view, actually harms the abstractions in Lisp, and we are actually back at the same page with all the other programming languages.

Also, when you are promoting something, it might not a good idea to compare against Python when it comes to speed, but when talking maintainability, only C is talking as a target here.