How big is the performance gap between std::sort and std::stable_sort in practice?

Question

Both should run in O(n log n), but in general sort is faster than stable_sort. How big is the performance gap in practice? Do you have some experience about that?

I want

Answer 1

Was looking for something similar - but was surprised no one talked about Auxiliary space.

As I believe - the implementation of both stable_sort and sort is supposed to guarantee O(NlogN) for all (Best, Average & Worst) cases.

However, the difference exists in the Auxiliary space used. stable_sort needs an Auxiliary space of O(N).

May be the difference in performance lies in acquiring that space. :)
Otherwise, theoretically - they are supposed to be same w.r.t performance.

sort should do what you need unless you need this -> stable_sort preserves the relative order of the elements with equivalent values.