> I hardly ever bother optimizing my code anymore, with -O3 nothing I do ever really seems to make a difference.

Your choice of data structure or algorithm would…

Yes, true, though I consider that "structural/procedural" optimization as opposed to "technical" optimization.

This means, I won't bother using "inline" anymore, but I will consider how many subfunctions in total I'd call.

I find that I can sometimes get significant speedups by changing data access patterns when considering cache. I have found this to be the first and most valuable thing to tune, before attempting SIMD.

Interesting! Any rules-of-thumb you can share about that process?