为什么只在Windows Server 2008中第一次调用EXTERNAL WCF非常慢（20秒）？

Question

我有一个外部WCF从第二次调用工作，第一次很慢需要20秒。

我的web.config

https://drive.google.com/a/integrens.com/file/d/0B8Ix7-GIED4eUVdNOTNYN215RVU/view?usp=sharing

我的代码

string mensaje = "";
mensaje = DateTime.Now.ToString();

System.Net.ServicePointManager.UseNagleAlgorithm = true;
System.Net.ServicePointManager.Expect100Continue = false;
System.Net.ServicePointManager.CheckCertificateRevocationList = true;
EnvioSunat.billServiceClient obj = new EnvioSunat.billServiceClient();
//ASMX.billService obj = new ASMX.billService();
byte[] data = File.ReadAllBytes(@"C:\inetpub\wwwroot\ws_integrensfe\FacturaElectronica\20566598389-REDDIGITALDELPERUS.A.C\DocumentosElectronico\20566598389-01-FT01-00000012\20566598389-01-FT01-00000012.zip");
//obj.Open();                
var datarpta = obj.sendBill("20566598389-01-FT01-00000012.zip", data);
//obj.Close();
mensaje = mensaje + "-" + DateTime.Now.ToString();
Label1.Text = mensaje;