[gwbas1c]

Things like Big-O notation are part of introductory computer science classes and introductory algorithms classes.

BigO notation also applies when an algorithm is distributed and runs over a network. An algorithm that's O(n^2) will always be slower than an algorithm that's O(2n). You don't need to run benchmarks to find that out.

[baby]

Big O notation tells you nothing about throughput in normal conditions. It tells you things about throughput in asymptotic conditions.

[erwan]

The parent poster also forgets about constant factors anyway.