;; test.scm
(use miscmacros posix)

(define (test fn)
  (let* ((fd (file-open fn open/rdonly))
         (size (file-size fd))
         (str (file-read fd size)))
    (file-close fd)
    str))

(define (test2 fn)
  (with-input-from-file fn (cut read-string #f)))

(print "file-read")
(time (dotimes (i 100) (test "5.json")))

(print "read-string")
(time (dotimes (i 100) (test2 "5.json")))


;; test.py
import timeit

def test():
    with open("5.json") as fd:
        foo = fd.read()

print(timeit.timeit('test()', number=100, setup="from __main__ import test"))


;; Results

kooda@crocmou /t/json> csi -s test.scm
file-read
13.885s CPU time, 7.541s GC time (major), 16/0 mutations (total/tracked), 99/1 GCs (major/minor), maximum live heap: 149.82 MiB
read-string
50.264s CPU time, 14.572s GC time (major), 65636/10572 mutations (total/tracked), 239/7461 GCs (major/minor), maximum live heap: 129.11 MiB
kooda@crocmou /t/json> python3 test.py
21.95156424200104