[New-bugs-announce] [issue39168] Generic type subscription is a huge toll on Python performance

[Ruslan Dautkhanov]

New submission from Ruslan Dautkhanov <dautkhanov at gmail.com>:

Reported originally here - 
https://twitter.com/__zero323__/status/1210911632953692162

See details here
https://asciinema.org/a/290643

In [4]: class Foo: pass
In [5]: %timeit -n1_000_000 Foo()
88.5 ns ± 3.44 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

In [6]: T = TypeVar("T")
In [7]: class Bar(Generic[T]): pass
In [8]: %timeit -n1_000_000 Bar()
883 ns ± 3.46 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

Same effect in Python 3.6 and 3.8

----------
messages: 359049
nosy: Ruslan Dautkhanov
priority: normal
severity: normal
status: open
title: Generic type subscription is a huge toll on Python performance
type: performance
versions: Python 3.6, Python 3.7, Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue39168>
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