Why is creating a class in Python so much slower than instantiating a class?

Question

I found that creation of a class is way slower than instantiation of a class.

>>> from timeit import Timer as T
>>> def calc(n):
...     return         


        

Answer 1

A quick dis of the following functions:

def a():
    class Haha(object):
         pass



def b():
    Haha()

gives:

2           0 LOAD_CONST               1 ('Haha')
            3 LOAD_GLOBAL              0 (object)
            6 BUILD_TUPLE              1
            9 LOAD_CONST               2 (", line 2>)
            12 MAKE_FUNCTION            0
            15 CALL_FUNCTION            0
            18 BUILD_CLASS         
            19 STORE_FAST               0 (Haha)
            22 LOAD_CONST               0 (None)
            25 RETURN_VALUE        

and

2           0 LOAD_GLOBAL              0 (Haha)
            3 CALL_FUNCTION            0
            6 POP_TOP             
            7 LOAD_CONST               0 (None)
            10 RETURN_VALUE        

accordingly.

By the looks of it, it simply does more stuff when creating a class. It has to initialize class, add it to dicts, and wherever else, while in case of Haha() is just calls a function.

As you noticed doing garbage collection when it gets's too slow speeds stuff up again, so Marcin's right in saying that it's probably memory fragmentation issue.