比GetTickCount()能更靠谱一点的时钟计时timeGetTime()

比GetTickCount()能更靠谱一点的时钟计时，有大佬测试有多大优化吗？

unsigned long get_sys_reference_time()
{    // get the system reference time
#if WINDOWS
    return timeGetTime();
#elif MAC
static const double twoRaisedTo32 = 4294967296.;
    UnsignedWide ys;
    Microseconds(&ys);
    double r = ((double)ys.hi * twoRaisedTo32 + (double)ys.lo);
    return (unsigned long)(r / 1000.);
#endif
}