I am blown away by the amount of speed up provided by “use local variable” and “don’t access attribute”.

>>> import random
>>> import timeit
>>> def fun1():
...     for _ in range(10000):
...         random.random()
>>> def fun2():
...     r = random.random
...     for _ in range(10000):
...         r()
>>> timeit.timeit('fun1()', setup='from __main__ import fun1', number=1000)
1.3499903420000123
>>> timeit.timeit('fun2()', setup='from __main__ import fun2', number=1000)
0.7535411869999962
>>> from random import random
>>> def fun3():
...     for _ in range(10000):
...         random()
>>> timeit.timeit('fun3()', setup='from __main__ import fun3', number=1000)
0.8960432139999739