Benchmark for merging widget media

bench_Media_merge.py

import django
from django import forms
from django.conf import settings
from django.forms import Media


settings.configure()
django.setup()


def setup():
    widget1 = Media(css={"screen": ["c.css"], "all": ["d.css", "e.css"]})
    widget2 = Media(css={"screen": ["a.css"]})
    widget3 = Media(css={"screen": ["a.css", "b.css", "c.css"], "all": ["e.css"]})
    widget4 = Media(css={"all": ["d.css", "e.css"], "screen": ["c.css"]})
    merged = widget1 + widget2
    merged = merged + widget3
    merged = widget1 + widget4
    return merged


def test(merged):
    merged._css


if __name__ == "__main__":
    import pyperf
    runner = pyperf.Runner()
    runner.timeit("test merge",
            "test(merged)", setup="from __main__ import test, setup; merged = setup()"
        )

Before

.....................
test merge: Mean +- std dev: 47.4 us +- 0.3 us

After

.....................
test merge: Mean +- std dev: 41.1 us +- 0.4 us

13% quicker