如何优化这个HTTP连接

我是c#编程的新手，我正试图了解如何优化这段代码，它总是被调用到一个线程中以从IP摄像机获取图像(快照)。我试图做一些优化，使更快的HTTP请求，但我看不到如何和在哪里行动。我可以问一下专家是否有办法得到这个结果吗?谢谢你。

private Image GetImage()
{
        HttpWebRequest req = null;
        Image img = null;
        HttpWebResponse res = null;
        try
        {
            req = WebRequest.Create(_httpCommand) as HttpWebRequest;
            req.Method = "GET";
            req.PreAuthenticate = true;
            req.AllowWriteStreamBuffering = true;
            req.Credentials = new NetworkCredential(_user, _pwd);
            res = req.GetResponse() as HttpWebResponse;
            using (Stream rs = res.GetResponseStream())
            {
                img = new Bitmap(rs);
            }
        }
        catch (Exception e) {
            _status = false; //<<------------------Signaling the FAILURE status! ---
            if (img != null)
                img.Dispose(); //<< for ------GC--------------
            //insert in LOG
            Log logItem = new Log(DateTime.Now, e.Message);
            AddLogItem(logItem);
        }
        return img;
}

req.Proxy = GlobalProxySelection.GetEmptyWebProxy();