直接上代码：
namespace ConsoleApp1{class Program{static void Main(string[] args){Console.WriteLine("正在计算Guid.....");Stopwatch stopwatch = new Stopwatch();stopwatch.Start();for (int i = 0; i < 10000000; i++){Guid guid = Guid.NewGuid();}stopwatch.Stop();TimeSpan t = stopwatch.Elapsed;string totaltime = String.Format("{0:00}:{1:00}:{2:00}:{3:00}", t.Hours, t.Minutes, t.Seconds, t.Milliseconds);Console.WriteLine("使用Guid时，总用时：{0}", totaltime);//2s//----------------------------------------------------------------------------------//Console.WriteLine("正在计算DateTime.....");stopwatch.Start();for (int i = 0; i < 10000000; i++){DateTime dateTime = DateTime.Now;}stopwatch.Stop();TimeSpan t2 = stopwatch.Elapsed;string totaltime2 = String.Format("{0:00}:{1:00}:{2:00}:{3:00}", t2.Hours, t2.Minutes, t2.Seconds, t2.Milliseconds);Console.WriteLine("使用DateTime时，总用时：{0}", totaltime2);//3sConsole.ReadKey();}}}
千万级别差一秒，再加一个零，差5s左右，所以用Guid比较合理！
