Silly program in dynamic language

gistfile1.lisp

;;; The Ubuntu image file is 564MB, the largest file close to 1G I could
;;; quickly find.
(defun process (&optional (file #p"~/Downloads/ubuntu-14.04-server-amd64.iso"))
  (declare (optimize (speed 3) (safety 1)))
  (with-open-file (in file :direction :input
                           :element-type 'unsigned-byte)
    (let ((buf (make-array #xffff :element-type '(unsigned-byte 8)))
          (result 0))
      (loop for read = (read-sequence buf in)
            until (zerop read)
            do (loop for x across buf
                     do (setf result
                              (ldb (byte 8 0) (+ result x)))))
      result)))

#|
CL-USER> (time (process))
Evaluation took:
  0.658 seconds of real time
  0.659847 seconds of total run time (0.502664 user, 0.157183 system)
  100.30% CPU
  1,509,934,829 processor cycles
  27,936 bytes consed
|#

Not that I had to get out of my way to make the result be just one byte, not the actual sum of bytes.