如何提高Excel导出的效率

asp.net页面导出Excel，显示超时失败
但在数据库执行相关的存储过程不到3秒就可以执行完毕，输出行数1300多行导出的函数如下，大家看为什么会慢的到超时呢，是否有更好的办法：
public static void SaveAsFile(System.Data.DataTable dt, string fileName)
        {
            System.Web.UI.WebControls.GridView gv = new GridView();
            gv.DataSource = dt.DefaultView;
            gv.AllowPaging = false;
            gv.HeaderStyle.BackColor = System.Drawing.Color.Green;
            gv.HeaderStyle.HorizontalAlign = HorizontalAlign.Center;
            gv.HeaderStyle.Font.Bold = true;
            gv.DataBind();
            try
            {
                System.Web.HttpContext.Current.Response.Clear();
                System.Web.HttpContext.Current.Response.Buffer = true;
                System.Web.HttpContext.Current.Response.Charset = "GB2312"; //设置了类型为中文防止乱码的出现                 System.Web.HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");//设置输出流为简体中文 
                System.Web.HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8) + ".xls"); //定义输出文件和文件名                 System.Web.HttpContext.Current.Response.ContentType = "application/ms-excel";//设置输出文件类型为excel文件。 
                gv.EnableViewState = false;
                System.Globalization.CultureInfo myCItrad = new System.Globalization.CultureInfo("ZH-CN", true);
                System.IO.StringWriter oStringWriter = new System.IO.StringWriter(myCItrad);
                System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);
                gv.RenderControl(oHtmlTextWriter);
                System.Web.HttpContext.Current.Response.Write(oStringWriter.ToString());
                //HttpContext.Current.ApplicationInstance.CompleteRequest(); 
                System.Web.HttpContext.Current.Response.End();
            }
            catch (System.Exception ee)
            {
                string ddd = ee.Message;
            }
        }