profile_chars_lookups.py

from timeit import Timer


# ........................................................................... #
FORBIDDEN_CHARS = \
    ('!',
     '@',
     '#',
     '$',
     '%',
     '^',
     '&',
     '*',
     '(',
     ')',
     '_',
     '+',
     '-',
     '=',
     '[',
     ']',
     '{',
     '}',
     ';',
     ':',
     "'",
     '"',
     '\\',
     '|',
     '~',
     '`',
     '<',
     '>',
     ',',
     '.',
     '/',
     '?',
    )

TEST_STRING = "Lorem ipsum Sit qui non ex dolor dolore eu adipisicing exercitation culpa dolor eu reprehenderit deserunt Ut cillum minim dolor aute cillum sunt ex est labore sint in ut dolore Excepteur ullamco officia eu sint Excepteur ut mollit ut."

ITERATIONS = 1000000
REPEAT_TIMES = 3

# ........................................................................... #
# this is "SLOW", assuming you know what slow means and care
def two_level_lookup():
    for char in FORBIDDEN_CHARS:
        if char in TEST_STRING:
            pass

# ........................................................................... #
def main():
    timer = Timer("two_level_lookup()", "from __main__ import two_level_lookup")
    print("go through " + str(ITERATIONS) + " iterations, " + str(REPEAT_TIMES) + " times")
    results = timer.repeat(3, number=ITERATIONS)
    print(results)
    # calculate how long one iteration took, using first result
    print("1 iteration took:" + '{0:f}'.format((results[0] / ITERATIONS)) + " of a second")


# @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ #
if __name__=='__main__':
    main()

shell_run

$ python2 profile_chars.py 
go through 1000000 iterations, 3 times
[17.295485973358154, 17.31608295440674, 17.370513916015625]
Iteration took:0.000017 of a second

$ python3 profile_chars.py 
go through 1000000 iterations, 3 times
[5.974218010989716, 5.972314420010662, 5.972688858979382]
1 iteration took:0.000006 of a second