[plt-scheme] Memory Leak Specifics

Ok, I've isolated my memory leak down to the following code example.  If I
let this run, my memory use skyrockets.  Any ideas?  Thanks, -Zach

;; a random scheme expression
(define p '(lambda (a b c)
  (or (not b)
      (or (not a)
          (or (not #t) (or #t (or (not #f) (or (not #f) (or (not a) (or #t
(or #f (not b))))))))))))

;; a placeholder
(define e '())

;; evaluate the expression over and over
(let loop ((i 10000))
    (set! e (eval p))
    (if (not (equal? i 0)) (loop (- i 1))))