Check out https://github.com/mietek/mit-cadr-system-software https://github.com/mietek/mit-cadr-system-software Itss a tape dump of the CADR system. Also you co

Check out https://github.com/mietek/mit-cadr-system-software https://github.com/mietek/mit-cadr-system-software Itss a tape dump of the CADR system. Also you could check out OpenGenera, but it's not (legally) available. If you want modern examples, check out SBCL, the Common Lisp compiler https://github.com/sbcl/sbcl https://github.com/sbcl/sbcl While a Scheme and not a Lisp, you can check out Gambit Scheme. https://github.com/gambit/gambit https://github.com/gambit/gambit It's written in a functional style and compiles Scheme to C. The generated code is really fast. As an aside, there really should be no difference in performance between a loop and a tail recursive call, assuming the compiler does TCO. So if that's your definition of "functional", then it should have the same performance as any "imperative" language.