Lists vs. StringIO vs. Regular String Concat for building strings in Python

performance_results.txt

IPython 0.10.1 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object'. ?object also works, ?? prints more.

In [2]: from string_building_perf import *

In [3]: %timeit build_ul_list(100000)
10 loops, best of 3: 77.9 ms per loop

In [4]: %timeit build_ul_stringio(100000)
10 loops, best of 3: 109 ms per loop

In [5]: %timeit build_ul_concat(100000)
10 loops, best of 3: 66.1 ms per loop

In [6]: %timeit build_ul_list(100000, get_random_word)
1 loops, best of 3: 245 ms per loop

In [7]: %timeit build_ul_stringio(100000, get_random_word)
1 loops, best of 3: 269 ms per loop

In [8]: %timeit build_ul_concat(100000, get_random_word)
1 loops, best of 3: 203 ms per loop

string_building_perf.py

from cStringIO import StringIO
from itertools import permutations
import string
import random


word = 'x' * 8
words = [''.join(p) for p in permutations(string.letters[:8])]


def get_8x():
    return word


def get_random_word():
    return random.choice(words)


def build_ul_list(linect, get_word=get_8x):
    buffer = ['<ul>\n']
    for i in xrange(linect):
        buffer.append('<li>%s</li>\n' % get_word())
    buffer.append('</ul>')
    return ''.join(buffer)


def build_ul_stringio(linect, get_word=get_8x):
    buffer = StringIO()
    buffer.write('<ul>\n')
    for i in xrange(linect):
        buffer.write('<li>%s</li>\n' % get_word())
    buffer.write('</ul>')
    return buffer.getvalue()


def build_ul_concat(linect, get_word=get_8x):
    buffer = '<ul>\n'
    for i in xrange(linect):
        buffer += ('<li>%s</li>\n' % get_word())
    buffer += '</ul>'
    return buffer