====== Execution time ======

===== DateTime.UtcNow =====
  * very fast
  * bad resolution (10 milliseconds)

<code csharp>
DateTime begin = DateTime.UtcNow;
...
DateTime end = DateTime.UtcNow;
Console.WriteLine("Execution time: " + (end-begin).TotalMilliseconds + " ms.");
</code>

===== Stopwatch =====
  * little bit slower
  * can be unreliable on a PC with multiple processors or on processors with unconstant clock speed!

<code csharp>
Stopwatch watch = new Stopwatch();
watch.Start();
...
watch.Stop();
Console.WriteLine("Execution time: " + watch.Elapsed.TotalMilliseconds + " ms.");
</code>
 
===== Process.TotalProcessorTime =====
  * measures only processors time kept by process
  * if process is keeping multiple processors busy, the time of each processor will be added

<code csharp>
TimeSpan begin = Process.GetCurrentProcess().TotalProcessorTime;
...
TimeSpan end = Process.GetCurrentProcess().TotalProcessorTime;
Console.WriteLine("Execution time: " + (end - begin).TotalMilliseconds + " ms.");
</code>

===== References =====

  * [[http://kristofverbiest.blogspot.com/2008/10/beware-of-stopwatch.html]]