+

https://www.bilibili.com/read/cv15764722
速度最慢 28s

my_str = ''
for s in string_list:
        my_str += s + ' '

str.join()

慢5倍 0.5s

my_str = ''
for s in test_string_list:
        my_str.join(s)
        my_str.join(' ')

io.StringIO

速度最快 0.09s

output = io.StringIO()
for s in test_string_list:
    output.write(s)
    output.write(' ')
result = output.getvalue()