list_add_timings.py

from timeit import Timer
from functools import partial

def add_string(n):
    s = ''
    for _ in range(n):
        s += ' '

def add_string_in_list(n):
    l = ['']
    for _ in range(n):
        l[0] += ' '

Timer(partial(add_string, 1000000)).timeit(1)
#>>> 0.1848409200028982
Timer(partial(add_string, 10000000)).timeit(1)
#>>> 1.1123797750042286

Timer(partial(add_string_in_list, 10000)).timeit(1)
#>>> 0.0033865350123960525
Timer(partial(add_string_in_list, 100000)).timeit(1)
#>>> 0.25131178900483064