str performance in python

Question

While profiling a piece of python code (python 2.6 up to 3.2), I discovered that the str method to convert an object (in my case an intege

Answer 1

One reason that comes to mind is the fact that str(100000) involves a global lookup, but "%s"%100000 does not. The str global has to be looked up in the global scope. This does not account for the entire difference:

>>> Timer('str(100000)').timeit()
0.2941889762878418
>>> Timer('x(100000)', 'x=str').timeit()
0.24904918670654297

As noted by thg435,

>>> Timer('"%s"%100000',).timeit()
0.034214019775390625
>>> Timer('"%s"%x','x=100000').timeit()
0.2940788269042969