from timeit import Timer
t1=Timer("random.shuffle(l)", "import random; l = list(range(100000))")
t2=Timer("random.shuffle(l, random = random.random)", "import random; l = list(range(100000))")
print "With default rand: %s" % t1.repeat(10,1)
print "With custom rand: %s" % t2.repeat(10,1)