Python dictionary (dict) traversal of four methods performance test reports _python

In Python, there are four ways to traverse Dict. But what about the performance of these four kinds of traversal? I did the following tests

L = [(x,x) for X-xrange (10000)]
d = dict (l) From time

import Clock

t0=clock () to
i in D:
 t = i + D [I]
T1=clock () for

k,v in D.items ():
 t = k + v
t2=clock () for

k,v in D.iteritems ():
 t = k + v
t3=cl Ock ()

for k,v in Zip (D.iterkeys (), D.itervalues ()):
 t = k + v
t4=clock ()

print t1-t0, t2-t1, t3-t2, T4 -t3

Run this script 5 times, and the result is as follows:

Python test.py
0.00184039735833 0.00326492977712 0.00214993552657 0.00311549755797

python test.py
0.00182356570728 0.00339342506446 0.00234863111466 0.00321566640817

python test.py
0.00185107108827 0.00324563495762 0.00211175641563 0.00313479237748

python test.py
0.0018215130669 0.00320950848705 0.00215814608806 0.00322798225041

python test.py
0.00216635664955 0.00391807994377 0.00207604047314 0.00322757172233

Obviously the first method is the most efficient, and the third approach is slightly but almost the same, method 24 performance is much worse
But the actual difference is not too big, not too tangled