C# 中限制下载速度

/// <summary>
/// 速度限制、资源占用小
/// </summary>
/// <param name="_Request">Page.Request对象</param>
/// <param name="_Response">Page.Response对象</param>
/// <param name="_fileName">下载文件名</param>
/// <param name="_fullPath">带文件名下载路径</param>
/// <param name="_speed">每秒允许下载的字节数</param>
/// <returns>返回是否成功</returns>
public static bool ResponseFile(HttpRequest _Request, HttpResponse _Response, string _fileName, string _fullPath, long _speed)
{
    try
    {
        FileStream myFile = new FileStream(_fullPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
        BinaryReader br = new BinaryReader(myFile);
        try
        {
            _Response.AddHeader("Accept-Ranges", "bytes");
            _Response.Buffer = false;
            long fileLength = myFile.Length;
            long startBytes = 0;
 
            int pack = 10240;
            //int sleep = 200; 
            int sleep = (int)Math.Floor((double)(1000 * pack / _speed)) + 1;
            if (_Request.Headers["Range"] != null)
            {
                _Response.StatusCode = 206;
                string[] range = _Request.Headers["Range"].Split(new char[] { '=', '-' });
                startBytes = Convert.ToInt64(range[1]);
            }
            _Response.AddHeader("Content-Length", (fileLength - startBytes).ToString());
            if (startBytes != 0)
            {
                _Response.AddHeader("Content-Range", string.Format(" bytes {0}-{1}/{2}", startBytes, fileLength - 1, fileLength));
            }
            _Response.AddHeader("Connection", "Keep-Alive");
            _Response.ContentType = "application/octet-stream";
            _Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(_fileName, System.Text.Encoding.UTF8));
 
            br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
            int maxCount = (int)Math.Floor((double)((fileLength - startBytes) / pack)) + 1;
 
            for (int i = 0; i < maxCount; i++)
            {
                if (_Response.IsClientConnected)
                {
                    _Response.BinaryWrite(br.ReadBytes(pack));
                    Thread.Sleep(sleep);
                }
                else
                {
                    i = maxCount;
                }
            }
        }
        catch
        {
            return false;
        }
        finally
        {
            br.Close();
            myFile.Close();
        }
    }
    catch
    {
        return false;
    }
    return true;
}