关于 GetRequestStream（） 需要等待的问题（在线等）

Question

大哥们帮我看看下面这段程序　为什么经常在
                Stream outstream = request.GetRequestStream();
这一行要等待很长时间呢？一般需要２０秒左右
我把 request.Timeout 设小了也没有用。大多数时间一下通过，有时要等，然后抛出异常。
        public  StreamReader GetPage(string pageUrl,string postData)
        {
            HttpWebResponse response = null;
            HttpWebRequest request = null;
            StreamReader sr = null;
            CookieContainer cookieContainer = new CookieContainer();
            Encoding encoding = Encoding.GetEncoding("gb2312");            byte[] data = encoding.GetBytes(postData);
            request = WebRequest.Create(pageUrl) as HttpWebRequest;
            request.CookieContainer = cookieContainer;
            request.AllowAutoRedirect = true;
            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";
            if (this.Cookies != null)
                request.CookieContainer = this.Cookies;
            else
            {
                request.CookieContainer = new CookieContainer();
                this.Cookies = request.CookieContainer;
            }
            request.ContentLength = data.Length;
            request.Timeout = 5;
            try
            {
                Stream outstream = request.GetRequestStream();
                outstream.Write(data, 0, data.Length);
                outstream.Close();
                //发送请求并获取相应回应数据 
                response = request.GetResponse() as HttpWebResponse;
                //读取页面内容
                Stream instream = response.GetResponseStream();
                sr = new StreamReader(instream, System.Text.Encoding.Default);
            }
            catch (Exception)
            {
                //..........................
            }
            return sr;
            
        }