Yes a library author can spend a lot of time refining and optimising their generic data structure, but can never escape that it is generic. No amount of optimi

Yes a library author can spend a lot of time refining and optimising their generic data structure, but can never escape that it is generic. No amount of optimisation will make a hash table designed for items to be removed competitive with one where items do not need to be removed. >Take C++ for instance, not only is it possible to specialize generic code for particular types, but it's absolutely routine to do so. So it's not a generic data structure, then. When you specialise a template, you essentially write a concrete data structure for a particular type. Rather than writing a big generic data structure that's inefficient then specialise it to the particular type, it is much easier just to write that specialised data structure in the first place. >std::unordered_map is a strawman. There are a plethora of generic C++ hash tables which would match, if not soundly outperform, their C counterpart. How is it a strawman? It's in the standard library. >Also, even if we blindly accepted your claim, then how do you explain qsort often being beaten by std::sort or printf and its variants being crushed by libfmt? printf is on the order of 50 years old. libfmt as written about 5 minutes ago. Do you take into account in your comparison the many more years in which printf has been useful? Do you take into account the amount of time it takes printf to compile vs a huge C++ library like libfmt? Do you take into account all the code that has been slowed down by C++ programmers writing bad code and assuming a sufficiently smart compiler will inline everything for them? Do you take into account all the horrifically slow iostreams code out there? qsort and std::sort do completely different things. Comparing them is absurd. qsort takes the size and comparison operator at runtime. std::sort requires them to be specified at compile times. I frequently use qsort in a way that you simply could not use std::sort, because those things are runtime-variable. The proper comparison to std::sort is the implementation of a sorting algorithm written in C, specialised to the code it was written to work with. Then you can debate 'is it worth using this for the minor performance gain' etc. But comparing it to qsort is inane and demonstrates you don't even know what the two functions do.