[JohnBooty]

    with some being slower than others.

Do we all agree that in practice, these sort of micro-optimizations almost never matter?

It's certainly easy to think of situations where they do matter, but unless your project is FaaS (Fibonacci As A Service) probably not.

[itake]

I've seen that more than a few cases where people used the wrong data structure (like array, for O(N)) look ups, instead of a hash.

All the inefficiencies add up, at scale. a 3% inefficiency means you're spending ~3% more on compute. CI takes longer. Dev velocity decreases.