Python3 string index lookup vs bytes index lookup

lookups.py

from random import choice
from datetime import datetime
from string import ascii_letters, digits


def generate_string(length, choices=ascii_letters + digits):
    return ''.join(choice(choices) for _ in range(length))


def compare_lookup(length):
    print('Allocating memory...')
    mystring = generate_string(length)
    mybytes = mystring.encode('utf-8')
    print('Go!')

    start = datetime.now()
    for index in range(length):
        at_index = mystring[index]  # noqa
    string_lookup = datetime.now() - start

    start = datetime.now()
    for index in range(length):
        at_index = mybytes[index]  # noqa
    bytes_lookup = datetime.now() - start

    print('String lookup: {} ms'.format(
        string_lookup.total_seconds())
    )
    print('Bytes lookup : {} ms'.format(
        bytes_lookup.total_seconds())
    )


compare_lookup(10000000)

$ python3 lookups.py
Allocating memory...
Go!
String lookup: 0.513942 ms
Bytes lookup : 0.486462 ms