[hayley-patton]

> To optimize this further, you need implementation dependent code and replace abstractions of S-expressions with native machine code

This can be done by a program called a compiler. There are many compilers for Lisp.

(In other words, the same argument applies to every language ever which doesn't exactly correspond to machine code.)

[a2code]

And yet to extend Python, for example, you write code once. To extend Lisp, you have to extend a multiplicity of implementations you find relevant.