Comment by masklinn

> But is quadratic the real issue ?

Yes. That is literally the entirety of the issue: online loading takes 5mn because there are two accidentally quadratic loops which spin their wheel.

> The best algorithm for small, medium or a large size are not the same and generally behave poorly in the other cases.

“Behaves poorly” tends to have very different consequences: an algorithm for large sizes tends to have significant set up and thus constant overhead for small sizes. This is easy to notice and remediate.

A naive quadratic algorithm will blow up your production unless you dev with production data, and possibly even then (if production data keeps growing long after the initial development).