Compare performance of malloc, new and std::vector::resize().

vector_resize_bench.cc

#include <cstdlib>
#include <iostream>
#include <string>
#include <vector>

int main(int argc, char** argv) {
    std::string mode(argv[1]);
    size_t size(std::stoi(argv[2]));

    if (mode == "malloc") {
        char* foo = (char*)malloc(size);
    } else if (mode == "new") {
        char* foo = new char[size];
    } else if (mode == "vector") {
        std::vector<char> foo;
        foo.resize(size);
    } else {
        std::cerr << "Unknown mode. Valid modes are: malloc, new, vector" << std::endl;
    }
}

Numbers from Late 2013 MBP (Haswell):

$ /usr/bin/time ./a.out malloc 1000000000
    0.00 real         0.00 user         0.00 sys
$ /usr/bin/time ./a.out new    1000000000
    0.00 real         0.00 user         0.00 sys
$ /usr/bin/time ./a.out vector 1000000000
    2.98 real         2.59 user         0.36 sys