import timeit
setup = """
import random
import collections
class User(object):
  def __init__(self, a, b):
    self.a = a  # Always a bool
    self.b = b  # Always a bool
user_list = [ User( r % 2 == 0, r % 3 == 0 ) for r in (random.randint(0,100) for x in xrange(100)) ]
"""
stmt = """
a_count = collections.Counter()
b_count = collections.Counter()
 
for user in user_list:
    a_count.update([user.a])
    b_count.update([user.b])
"""
print timeit.timeit(setup=setup, stmt=stmt, number=1000)

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