从sharepoint asset library下载文件为什么总是花了很长的时间？
我在我的项目中使用了一个button，叫download，里面会去根据一个url去下载这个文件，代码如下，现在的问题是为什么在IE8下面会花费很长时间（接近半分钟），在火狐下一瞬间就下载完毕了，我的代码是不是有什么问题？
求解释。。。 求高手！

public void OpenAttachment(string url, string picName)
{
try
{
//set the content type of file according to extension
string[] fext = picName.Split('.');

// Get the extension of File to determine the file type
string casestring = "";
if (fext.Length > 1)
{
casestring = fext[fext.Length - 1];
}

SPWeb web = SPContext.Current.Web;
web.AllowUnsafeUpdates = true;
string contentType = "";

SPFile tempFile = web.GetFile(url);

byte[] obj = (byte[])tempFile.OpenBinary();
switch (casestring)
{

case "jpg": contentType = "image/jpeg";

break;

case "jpeg": contentType = "image/jpeg";

break;

case "gif": contentType = "image/gif";

break;

case "bmp": contentType = "image/bmp";

break;

case "png": contentType = "image/x-png";

break;

case "tif": contentType = "image/tiff";

break;

case "flv": contentType = "video/x-flv";

break;
}

HttpContext.Current.Response.ClearContent();
HttpContext.Current.Response.ClearHeaders();
HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment; filename= " + picName);
HttpContext.Current.Response.ContentType = contentType;

//Check that the client is connected and has not closed the connection after the request

if (HttpContext.Current.Response.IsClientConnected)
HttpContext.Current.Response.BinaryWrite(obj);

HttpContext.Current.Response.Flush();
HttpContext.Current.Response.Close();

web.AllowUnsafeUpdates = false;
}

catch (Exception ex)
{
Response.Write(ex.ToString());
}

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