class-based context managers are faster than generator-based ones

main.py

# CPython3.8.12 上で測ったところclass-basedの方が17倍近く速かった

from functools import partial
from contextlib import contextmanager
from timeit import timeit


class class_based:
    __slots__ = tuple()

    def __enter__(self):
        pass

    def __exit__(self, exc_type, exc_val, exc_tb):
        pass


@contextmanager
def generator_based():
    yield


def use_context_manager(context_manager):
    with context_manager():
        pass


t_class = timeit(partial(use_context_manager, class_based))
t_generator = timeit(partial(use_context_manager, generator_based))
print(f"{t_class = }")
print(f"{t_generator = }")