> Half of a second is very noticeable (and annoying). I had similar perception in my previous work.

That's because it has to load django and the whole django project. Here's click:

    > time python test.py --help
    Usage: test.py [OPTIONS]

    Options:
      --help  Show this message and exit.
    python test.py --help  0.06s user 0.02s system 95% cpu 0.078 total

and argparse:

    > time python test.py --help
    usage: test.py [-h]

    optional arguments:
      -h, --help  show this help message and exit
    python test.py --help  0.03s user 0.02s system 93% cpu 0.054 total

reference:

    > time python -c 'print "hello"'
     hello
    python -c 'print "hello"'  0.01s user 0.01s system 88% cpu 0.025 total