winforms正则表达式下载数据速度慢

Question

 HttpWebRequest request = (HttpWebRequest)WebRequest.Create(_url);
            request.UserAgent = "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.1.1) Gecko/20090715 Firefox/3.5.1 (.NET CLR 3.5.30729)";
            request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
            request.Headers["Accept-Language"] = "zh-cn,zh;q=0.5";
            request.Headers["Accept-Charset"] = "GB2312,utf-8;q=0.7,*;q=0.7";
            request.Headers["Cookie"] = "PriceStyle=decimal; Culture=zh-TW;";
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            Stream stream = response.GetResponseStream();
            StreamReader reader = new StreamReader(stream);
            return reader.ReadToEnd();
            return "";代码是这样我是这样下载的