My self written RollingHash was slower than SHA-1… (written ~2007)

hashbench.py

import hashlib
from backup import hashes
import timeit

import cProfile

def rechne_sha(filename):
    block = open(filename, "rb").read()
    for i in range (512,len(block)):
        [hashlib.sha1(block[i:i+512]).hexdigest()]
    
    
def rechne_wh(filename):
    block = open(filename, "rb").read()
    wh = hashes.RollingHash(block[0:512])
    # speed: take method lookup out of loop
    wu = wh.update
    for i in range (512,len(block)):
        wu(block[i])
    
ts = timeit.Timer('rechne_sha("Beispiel.pdf")', 'from __main__ import rechne_sha')
tw = timeit.Timer('rechne_wh("Beispiel.pdf")', 'from __main__ import rechne_wh')

anzahl = 10

def runner(anzahl):
    for i in range(0, anzahl):
        rechne_wh("Beispiel.pdf")

print "Sha1:\t%s\nWH:\t%s" %(ts.timeit(anzahl), tw.timeit(anzahl))

cProfile.run('runner(10)')


#    Sha1:    5.26615405083
#    WH:      2.6121430397
#             3384084 function calls in 3.717 CPU seconds
#    
#       Ordered by: standard name
#    
#       ncalls  tottime  percall  cumtime  percall filename:lineno(function)
#            1    0.000    0.000    3.717    3.717 <string>:1(<module>)
#           10    0.508    0.051    3.716    0.372 cryptbench.py:13(rechne_wh)
#            1    0.000    0.000    3.717    3.717 cryptbench.py:26(runner)
#           10    0.000    0.000    0.002    0.000 hashes.py:27(__init__)
#           10    0.000    0.000    0.002    0.000 hashes.py:42(_digest)
#       845990    2.639    0.000    3.190    0.000 hashes.py:50(update)
#           20    0.000    0.000    0.000    0.000 {len}
#           10    0.001    0.000    0.001    0.000 {map}
#       845990    0.113    0.000    0.113    0.000 {method 'append' of 'list' objects}
#            1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler' objects}
#       845990    0.333    0.000    0.333    0.000 {method 'pop' of 'list' objects}
#           10    0.003    0.000    0.003    0.000 {method 'read' of 'file' objects}
#           10    0.000    0.000    0.000    0.000 {open}
#       845990    0.104    0.000    0.104    0.000 {ord}
#           21    0.014    0.001    0.014    0.001 {range}
#           20    0.001    0.000    0.001    0.000 {sum}