But the thing that unites these tools is that they are grafts: they are Lisp tools that run inside C-based OSes which come from a profoundly different school of computer design.

Please stop with this rubbish narrative - you even say later that Medley supports Common Lisp, and the Maclisp Lisp machine lineage did too. They’re all von Neumann, so not that profoundly different either. (See prior on RISC and high level languages too.)

Behold, a Lisp:

(identification-division
 (program-id :hello-world))
(procedure-division
 (main
  (display "Hello, world!")
  (stop run)))

ISWIM

Without type declarations I have CCL computing (fib 39) in 0.365 seconds and (fib 39) in 0.743 seconds. This is because CCL inlines the fixnum case for generic addition, and SBCL does not.