Hmm.

Since I control the VM anyway, it may be possible for me to add some sort of feature/bytecode/built-in-function that can perform reduction of arguments without consing (i.e. just by allocating a continuation function and reusing it). It would be possible to also have it "short-circuit" so to speak, prevent it from allocating a new closure and just pass its own called continuation directly to the child function.

Basically it would be like this:

  (with (f0 (fn () (handle-0-arguments))
         f1 (fn (a) (handle-1-argument a))
         f2 (fn (a b) (handle-2-arguments a b)))
    (fn rest ; not actually expanded into a list
      ; this will be implemented in C
      (if
        (no rest)
          (f0) ; pass the continuation
        (no (cdr rest))
          (f1 (car rest))
        (no (cdr:cdr rest))
          (f2 (car rest) (cadr rest))
        ; perform reduction
          (ccc
            ; enclose these variables
            (with (a (f2 (car rest) (cadr rest))
                   rest (cdr:cdr rest))
              ; also enclose the continuation
              (afn (k)
                (zap a (f2 (car rest) (cadr rest)))
                    ; rest will be an index into the
                    ; closure variables
                (if (zap cdr rest)
                    (self k)
                    (k a)))))))))