Regular expression benchmark in C++

RegExBenchmark.cpp

#include "stdafx.h"

#include <windows.h>
#include <regex>
#include <vector>
#include <string>
#include <fstream>
#include <cstdio>
#include <codecvt>

using namespace std;

wstring load(wstring filename) {
    const locale empty_locale = locale::empty();
    typedef codecvt_utf8<wchar_t> converter_type;
    const converter_type* converter = new converter_type;
    const locale utf8_locale = locale(empty_locale, converter);
    wifstream in(filename);
    wstring contents;
    if (in)
    {
        in.seekg(0, ios::end);
        contents.resize(in.tellg());
        in.seekg(0, ios::beg);
        in.read(&contents[0], contents.size());
        in.close();
    }
    return(contents);
}

int count(const wstring &re, const wstring &s){
    static const wregex rsplit(re);
    auto rit = wsregex_token_iterator(s.begin(), s.end(), rsplit, -1);
    auto rend = wsregex_token_iterator();
    int count=0;
    for (auto it=rit; it!=rend; ++it)
        count += it->length();
    return count;
}

int _tmain(int argc, _TCHAR* argv[])
{
    wstring str = load(L"pg10.txt");
    wstring re = load(L"re.txt");

    __int64 freq, tStart, tStop;
    unsigned long TimeDiff;
    QueryPerformanceFrequency((LARGE_INTEGER *)&freq);
    QueryPerformanceCounter((LARGE_INTEGER *)&tStart);

    vector<int> res(4);

#pragma omp parallel num_threads(4)
    for(auto i=0; i<res.size(); ++i)
        res[i] = count(re, str);

    QueryPerformanceCounter((LARGE_INTEGER *)&tStop);
    TimeDiff = (unsigned long)(((tStop - tStart) * 1000000) / freq);
    printf("(%d, %d, %d, %d) %fs\n", res[0], res[1], res[2], res[3], TimeDiff/1e6);
    return 0;
}