Why is the first request I do with a WebClient object always taking 15 seconds?

I'm talking about POST requests, using:

WebClient wc = new WebClient();
String result = wc.UploadString("http://example.com/", "data=hello, world!");

Edit: This is my actual code right now:

String result;
using (WebClient wc = new WebClient())
{
    result = wc.UploadString("http://" + "pastebin.com/api_public.php", "POST", "paste_code=" + LongDataEscape(Clipboard.GetText()));
}

And if you're wondering about LongDataEscape:

    public String LongDataEscape(String Str)
    {
        String Output = "";
        int ByteCount = 32766;
        if (Str.Length > ByteCount)
        {
            for (int i = 0; i < Str.Length; i+= ByteCount)
            {
                if (Str.Length - i < ByteCount)
                    Output += Uri.EscapeDataString(Str.Substring(i, Str.Length - i));
                else
                    Output += Uri.EscapeDataString(Str.Substring(i, ByteCount));
            }
        }
        else
            Output = Uri.EscapeDataString(Str);
        return Output;
    }

The first time I execute the above piece of code it always takes around 15 seconds (ok maybe 10), no matter what website it开发者_如何学Go is to, but the same code pieces that follow are just instantly.

I was thinking there might be some setting that does it, but I haven't found out yet.

---

I fixed it.

When you make a new WebClient object (FtpWebRequest too) you have to set the "Proxy" property of it to null. For example:

WebClient wc = new WebClient();
wc.Proxy = null;

Then the first request will never take long and you'll have no problems.

---

The first call often take longer than subsequent ones, however 15s is too much.

Try to make the following change:

using(WebClient wc = new WebClient())
{
    String result = wc.UploadString("http://example.com/", "data=hello, world!");
}