Скорость конкатенации строк и списков

 def concat_times():
    x = 'abc' * 10000
    y = 'def' * 10000
 
    time_start = datetime.datetime.now()
    z = x + y
    print(f'"+" Elapsed: {datetime.datetime.now() - time_start}') 

    time_start = datetime.datetime.now()
    z = "%s%s" % (x, y)
    print(f'"%" Elapsed: {datetime.datetime.now() - time_start}')

    time_start = datetime.datetime.now()
    z = "{}{}".format(x, y)
    print('"{}{}" Elapsed:', f'{datetime.datetime.now() - time_start}')

    time_start = datetime.datetime.now()
    z = "{0}{1}".format(x, y)
    print('"{0}{1}" Elapsed:', f'{datetime.datetime.now() - time_start}')

    time_start = datetime.datetime.now()
    z = f"{x}{y}"
    print('"{x}{y}" Elapsed:', f'{datetime.datetime.now() - time_start}')

>> concat_times()
"+" Elapsed: 0:00:00.000017
"%" Elapsed: 0:00:00.000013
"{}{}" Elapsed: 0:00:00.000019
"{0}{1}" Elapsed: 0:00:00.000012
"{x}{y}" Elapsed: 0:00:00.000008

def list_concat_times():
    x = [i for i in range(1000)]
    y = [i for i in range(1000)]
    z = []
    
    time_start = datetime.datetime.now()
    z = x + y
    print(f'"+" Elapsed: {datetime.datetime.now() - time_start}')
    print(f'z len: {len(z)}, x len: {len(x)}, y len: {len(y)}\n')

    c = None
    time_start = datetime.datetime.now()
    c = x.extend(y)
    print(f'"extend" Elapsed: {datetime.datetime.now() - time_start}')
    print(f'c None, x len: {len(x)}, y len: {len(y)}\n')

    x = [i for i in range(1000)]
    time_start = datetime.datetime.now()
    x.extend(y)
    print(f'"extend" Elapsed: {datetime.datetime.now() - time_start}')
    print(f'x len: {len(x)}, y len: {len(y)}')

"+" Elapsed: 0:00:00.000023
z len: 2000, x len: 1000, y len: 1000

"extend" Elapsed: 0:00:00.000013
c None, x len: 2000, y len: 1000

"extend" Elapsed: 0:00:00.000010
x len: 2000, y len: 1000