Is your std::vector<byte>::resize implementation optimal?

vector_resize_benchmark.cpp

// Is your C++11 std::vector<byte>::resize implementation optimal?
//
// Visual C++ 11:
//      reserve() -> fill_n -> detail: _Fill_n -> memset:
//
// inline unsigned char *_Fill_n(unsigned char *_Dest, size_t _Count, unsigned char _Val)
// {  // copy unsigned char _Val _Count times through [_Dest, ...)
//    _CSTD memset(_Dest, _Val, _Count);
//	  return (_Dest + _Count);
// }
//
#include <chrono>
#include <iostream>
#include <vector>

int main()
{
    struct elapsed
    {
        typedef std::chrono::high_resolution_clock tclock;
        typedef std::chrono::milliseconds tunit;
        std::chrono::time_point<tclock> start;
        elapsed() : start(tclock::now()) {}
        ~elapsed()
        {
            std::cout << "elapsed: "
                << std::chrono::duration_cast<tunit>(tclock::now()-start).count()
                << std::endl;
        }
    };

    typedef unsigned char byte_t;
    typedef std::vector<byte_t> v_t;

    auto p = [](v_t const& v)
    {
        std::cout << "vector size: " << v.size() << " capacity: " << v.capacity() << std::endl;
    };

    auto s = 4294967295UL;//4294967295UL;
    {
        std::cout << "array new: "<< s << std::endl;
        byte_t* p = nullptr;
        {
            elapsed e;
            p = new byte_t[s];
        }
        delete [] p; 
    }
    {
        std::cout << "array new with zero-init: "<< s << std::endl;
        byte_t* p = nullptr;
        {
            elapsed e;
            p = new byte_t[s]();
        }
        delete [] p;
    }
    {
        std::cout << "vector reserve: "<< s << std::endl;
        elapsed e;
        v_t v;
        v.reserve(s);
        p(v);
    }
    {
        std::cout << "vector construct: "<< s << std::endl;
        elapsed e;
        v_t v(s);
        p(v);
    }
    {
        std::cout << "vector resize: "<< s << std::endl;
        v_t v;
        p(v);
        elapsed e;
        v.resize(s);
        p(v);
    }

    return 0;
}

Visual C++ 11 - Release|x64

array new: 4294967295
elapsed: 0
array new with zero-init: 4294967295
elapsed: 2217
vector reserve: 4294967295
vector size: 0 capacity: 4294967295
elapsed: 3
vector construct: 4294967295
vector size: 4294967295 capacity: 4294967295
elapsed: 2629
vector resize: 4294967295
vector size: 0 capacity: 0
vector size: 4294967295 capacity: 4294967295
elapsed: 1952