how to avoid checking the same condition repeatedly ?

[Peter Cacioppi]

Nobody (yes, his name is Nobody) said:

"If you're sufficiently concerned about performance that you're willing to
trade clarity for it, you shouldn't be using Python in the first place."

I think the correct thing to say here is, IF you know this subroutine is a bottleneck, THEN probably this subroutine (or even the module it lives within) should be recoding in a language closer to the metal (like C).

I don't think it's correct to imply that people very concerned about performance should not use Python. (And I agree, Nobody implied that ;) But sometimes performance concerns require the bottleneck(s) be recoded in a manner that sacrifices readability for performance, to include a different language. Python generally plays well with other languages, no? So code it in Py, profile it, refactor the bottlenecks as needed.