tuple unpacking is slower than tuple(list comprehension)

Feature or enhancement

Proposal:

In []: %timeit (*(x**2 for x in range(1000)),)  # (A)
47.2 μs ± 1.18 μs per loop (mean ± std. dev. of 7 runs, 10,000 loops each)

In []: %timeit tuple(x**2 for x in range(1000))  # most idiomatic
45.4 μs ± 5.57 μs per loop (mean ± std. dev. of 7 runs, 10,000 loops each)

In []: %timeit (*[x**2 for x in range(1000)],)  # (B)
36.5 μs ± 77.8 ns per loop (mean ± std. dev. of 7 runs, 10,000 loops each)

In []: %timeit tuple([x**2 for x in range(1000)])  # fastest
33.8 μs ± 710 ns per loop (mean ± std. dev. of 7 runs, 10,000 loops each)

Currently (A) and (B) are slower than the last one, even though it doesn't need to be so. There doesn't seem to be any bottleneck such as global namespace lookup.

Also, we want people to write the most idiomatic code, so it would be preferable to make the most idiomatic version to be as fast as the fastest version. Possibly with something like

if tuple is builtins.tuple:
    MAGIC
else:
    code as usual...

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-149960

Empieza reproduciendo las cuatro expresiones de benchmark del issue y compara el desempaquetado de tuplas con la construcción de tuplas. Revisa el PR vinculado gh-149960 para comprobar el trabajo que ya está en curso; se considera terminado cuando la forma idiomática con generador ya no queda por detrás de la forma más rápida sin romper el comportamiento de fallback indicado.