l = [(x,x) for x in xrange(10000)]
d = dict(l)

from time import clock

t0=clock()
for 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=clock()

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

print t1-t0, t2-t1, t3-t2, t4-t3

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