iterate by chunks timings

import itertools
import timeit


def grouper_it(n, iterable):
    it = iter(iterable)
    while True:
        chunk_it = itertools.islice(it, n)
        try:
            first_el = next(chunk_it)
        except StopIteration:
            return
        yield itertools.chain((first_el,), chunk_it)

def grouper(n, iterable):
    it = iter(iterable)
    while True:
       chunk = tuple(itertools.islice(it, n))
       if not chunk:
           return
       yield chunk

def dummy_element_consumer(func, n=3, data_size=10000):
    for chunk in func(n, xrange(data_size)):
        for el in chunk:
            dummy = el

def dummy_chunk_consumer(func, n=3, data_size=10000):
    for chunk in func(n, xrange(data_size)):
        dummy = tuple(chunk)


for consumer in (dummy_element_consumer, dummy_chunk_consumer):
    print consumer.__name__
    for data_size, npasses in ((100, 10000), (10000, 1000)):
        print ' data_size: %s, passes: %s' % (data_size, npasses)
        for n in (3, 10, 100, 1000):
            print '  grouper   ', n, timeit.timeit(lambda : consumer(grouper, n, data_size), number=npasses)
            print '  grouper_it', n, timeit.timeit(lambda : consumer(grouper_it, n, data_size), number=npasses)

        print
------------------
Results:
dummy_element_consumer
 data_size: 100, passes: 10000
  grouper    3 0.75289614549
  grouper_it 3 0.682097099117
  grouper    10 0.283187205571
  grouper_it 10 0.287213798965
  grouper    100 0.137917801202
  grouper_it 100 0.132218313015
  grouper    1000 0.138246513214
  grouper_it 1000 0.133138039654

 data_size: 10000, passes: 1000
  grouper    3 7.03408728375
  grouper_it 3 6.03008289606
  grouper    10 2.48628471741
  grouper_it 10 2.28650824356
  grouper    100 1.05532127117
  grouper_it 100 0.764705173135
  grouper    1000 0.752920695266
  grouper_it 1000 0.611105924492

dummy_chunk_consumer
 data_size: 100, passes: 10000
  grouper    3 0.761046326397
  grouper_it 3 1.00031595122
  grouper    10 0.258946700939
  grouper_it 10 0.361995614131
  grouper    100 0.105095489586
  grouper_it 100 0.14534625367
  grouper    1000 0.105786698303
  grouper_it 1000 0.145586671485

 data_size: 10000, passes: 1000
  grouper    3 7.10003329424
  grouper_it 3 9.44492849201
  grouper    10 2.20704193098
  grouper_it 10 3.02586649712
  grouper    100 0.738520806174
  grouper_it 100 0.903916032582
  grouper    1000 0.385726813393
  grouper_it 1000 0.479506690848