When I implemented this, I did some minimal benchmarking. Realloc was easily fast enough to cover all my use cases. I am not Facebook who need to optimize the

When I implemented this, I did some minimal benchmarking. Realloc was easily fast enough to cover all my use cases. I am not Facebook who need to optimize the single last byte of their string type. For the fast case, there is the alternative API which allows one to keep track of the capacity, without having the cost of storing it in the type. But realloc also does overallocate a little bit, and for large blocks it would remap the pages. The inlining argument makes sense though. (Edit: Pushing and then popping a billion integers takes about 2 seconds with std::vector<int>, 10 with vec(int) and realloc each time, and 4.3 seconds with a simple preallocation logic that does not require a capacity on my laptop. Having a call to "rand" in it already adds more overhead.).