Fast HTTP call ASP.Net

I'm sending an HTTPWebRequest to a 3rd party with the code below. The response takes between 2 and 22 seconds to come back. The 3rd party claims that once they receive it, they are sending back a response immediately, and that none of their other partners are reporting any delays (but I'm not sure I believe them -- they've lied before).

HttpWebRequest request = (HttpWebRequest)WebRe开发者_StackOverflow社区quest.Create("https://www.example.com");
request.Timeout = 38000;
request.Method = "POST";
request.ContentType = "text/xml";
StreamWriter streamOut = new StreamWriter(request.GetRequestStream(), System.Text.Encoding.ASCII);
streamOut.Write(XMLToSend);     // XMLToSend is just a string that is maybe 1kb in size
streamOut.Close();
HttpWebResponse resp = null;
resp = (HttpWebResponse)request.GetResponse();      // This line takes between 2 and 22 seconds to return.
StreamReader responseReader = new StreamReader(resp.GetResponseStream(), Encoding.UTF8);
Response = responseReader.ReadToEnd();      // Response is merely a string to hold the response.

Is there any reason that the code above would just...pause? The code is running in a very solid hosting provider (Rackspace Intensive Segment), and the machine it is on isn't being used for anything else. I'm merely testing some code that we are about to put into production. So, it's not that the machine is taxed, and given that it is Rackspace and we are paying a boatload, I doubt it is their network either.

I'm just trying to make sure that my code is as fast as possible, and that I'm not doing anything stupid, because in a few weeks, this code will be ramped up to run 20,000 requests to this 3rd part every hour.

Try doing a flush before you close.

streamOut.Flush();
streamOut.Close();

Also download microsoft network monitor to see for certain if the hold up is you or them, you can download it here...

http://www.microsoft.com/downloads/en/details.aspx?FamilyID=983b941d-06cb-4658-b7f6-3088333d062f&displaylang=en

There is a few things that I would do:

1. I would profile the code above and get some definitive timings.
2. Implement the using statements in order to dispose of resources correctly.
3. Write the code in an async style there's going to be an awful lot of IO wait once its ramped.

Can you hit the URL in a regular ole browser? How fast is that?

Can you hit other URL's (not your partner's) in this code? How fast is that?

It is entirely possible you're getting bitten by the 'latency bug' where even an instant response from your partner results in unpredictable delays from your perspective.

Another thought: I noticed the https in your URL. Is it any faster with http?