std::vector::reserve + std::vector::push_back in loop is sub-optimal, because push_back needs to check for re-allocation, but that never comes.

std::vector::resize + std::vector::operator[] in loop is also sub-optimal, because resize default-initializes all elements only to be overwritten soon anyway.

This article’s author suggests push_back_unchecked.

I suggest std::vector::insert with pair of random access iterators with custom dereference operator that does the “transform element” or “generate element” functionality. The standard will have resize_and_overwrite hopefully soon.

Moar discussion:

https://codingnest.com/the-little-things-the-missing-performance-in-std-vector/

https://twitter.com/horenmar_ctu/status/1695823724673466532

https://twitter.com/horenmar_ctu/status/1695331079165489161

https://www.reddit.com/r/cpp/comments/162tohr/the_little_things_the_missing_performance_in/

https://www.reddit.com/r/cpp/comments/162tohr/the_little_things_the_missing_performance_in/jy21hgd/

https://twitter.com/basit_ayantunde/status/1644895468399337473

https://twitter.com/MarekKnapek/status/1645272474517422081

https://www.reddit.com/r/cpp/comments/cno9ep/improving_stdvector/