>>210 こんな感じかなぁ。
#include <iostream>
#include <windows.h>
using namespace std;

int main(void)
{
LARGE_INTEGER freq, now, old;
UINT r = 60;

QueryPerformanceFrequency(&freq);
while(!(GetKeyState(VK_RETURN) & 0x80)){
cout << "fps: " << r << endl;

QueryPerformanceCounter(&now);
while(now.QuadPart - old.QuadPart < freq.QuadPart / r){
QueryPerformanceCounter(&now);
}
QueryPerformanceCounter(&old);
}
return 0;
}