Response.Flush

 string str2 = "";
 for (int i = 0; i < 1000; i++)
            {
                str2 += "|bddaasdfkjsdlajlsjdfljfsdljsdf|\r\n";
                context.Response.Write(str2);
                context.Response.Flush();
                System.Threading.Thread.Sleep(5000);
            }