Pyhon 2.x or 3.x, which is faster?

[Jussi Piitulainen]

BartC writes:

> On 08/03/2016 02:47, MRAB wrote:
>> On 2016-03-08 01:33, BartC wrote:
>
>>> Compared with 2.7, 3.4 above is spending nearly an extra ten seconds
>>> doing .... what? I can't understand why someone just wouldn't care.
>>>
>> Part of it will be that Python 2 has 2 integer types: 'int' (fixed
>> length) and 'long' (variable length).
>>
>> Originally, 'int' addition could overflow, but it was more friendly to
>> promote the result to 'long' instead.
>
> That was my first thought on reading the thread and was going to post
> that as the reason for 3 being a little more sluggish.
>
> But then I tested Python 2 (2.7.11), and I couldn't get integer
> arithmetic to overflow at all!

It overflows to the long type.

Replace 0, 100000000 and 1 with 0L, 100000000L and 1L in Python2 version
of your while loop test to see the effect. When I tried it this morning,
it almost closed the gap between 2.7 and 3.4 on my laptop. (I don't
remember the minor versions.) The latter was still slower but not by
much.