Python Performance: Why 'if not list' is 2x Faster Than Using len()

[sohkamyung]

https://blog.codingconfessions.com/p/python-performance-why-if-not-list

[zahlman]

> But this isn’t just about coding style, one of these is ~2x faster than the other, see for yourself:

FWIW, it's not necessary to start an interpreter for this test.

  $ py3.13 -m timeit --setup "l = []" "not l"
  10000000 loops, best of 5: 20.7 nsec per loop
  $ py3.13 -m timeit --setup "l = []" "len(l) == 0"
  10000000 loops, best of 5: 31 nsec per loop

[odie5533]

The explanation is paywalled.

> This post is for paid subscribers.