NormalTimer timer1 = new NormalTimer();
            timer1.Start();
            for (int i = 0; i < 1000 * 1000 * 1000; i++) ;
            timer1.Stop();
            Console.WriteLine("Duration: {0} seconds", timer1.durationS);


            PrecisionTimer timer2 = new PrecisionTimer();
            timer2.Start();
            for (int i = 0; i < 1000 * 1000 * 1000; i++) ;
            timer2.Stop();
            Console.WriteLine("Duration: {0} seconds", timer2.durationS);

  internal class UnmanagedApi
  {
   [DllImport("Kernel32.dll")]
   internal static extern bool QueryPerformanceCounter(
    out long lpPerformanceCount);

   [DllImport("Kernel32.dll")]
   internal static extern bool QueryPerformanceFrequency(
    out long lpFrequency);
  }
 public class PrecisionTimer
 {
  private long startTick;
  private long stopTick;
  private long tickFrequency;
  public PrecisionTimer()
  {
   UnmanagedApi.QueryPerformanceFrequency(out tickFrequency);
  }
  internal class UnmanagedApi
  {
   [DllImport("Kernel32.dll")]
   internal static extern bool QueryPerformanceCounter(
    out long lpPerformanceCount);
   [DllImport("Kernel32.dll")]
   internal static extern bool QueryPerformanceFrequency(
    out long lpFrequency);
  }

  public void Start()
  {
   Thread.Sleep(0); //execute waiting threads first, then continue
   GC.Collect();
   GC.WaitForPendingFinalizers();
   GC.Collect();
   UnmanagedApi.QueryPerformanceCounter(out startTick);
  }

  public void Stop()
  {
   UnmanagedApi.QueryPerformanceCounter(out stopTick);
  }

  public static long Tick()
  {
   long retVal;
   UnmanagedApi.QueryPerformanceCounter(out retVal); 
   return retVal;
  }
  
  private long ticks
  {
   get
   {
    if (startTick > stopTick)
    {
     startTick = stopTick = 0;
     return 0;
    }
    else
    {
     return (stopTick - startTick);
    }
   }
  }
  public void WriteLine()
  {
   Console.WriteLine("{0} ms", durationMs);
  }
  public double durationS
  {
   get { return (double) ticks/tickFrequency; }
  }
  public double durationMs
  {
   get { return durationS*1000; }
  }
 }
 public class NormalTimer
 {
  private long startTick;
  private long stopTick;
  public void Start()
  {
   Thread.Sleep(0); //execute waiting threads first, then continue
   startTick = Environment.TickCount;
  }
  public void Stop()
  {
   stopTick = Environment.TickCount;
  }
  private long ticks
  {
   get
   {
    if (startTick > stopTick)
    {
     startTick = stopTick = 0;
     return 0;
    }
    else
    {
     return (stopTick - startTick);
    }
   }
  }

  public long durationMs
  {
   get { return ticks; }
  }
  public double durationS
  {
   get { return (double) ticks/1000; }
  }
 }