title: New HttpClient proxy settings issues
body: <p>I'm trying to rewrite old network authentication logic according to new fw 4.5 features such as HttpClient and await/async and i experience unexpected latency (around 15s) between request and response. My guess is that happens because client tries to find/use proxy from IE like it was with old HttpRequest/WebClient. Here's the code :</p>
  
  <pre><code>public static async Task&lt;AuthResult&gt; GetDataFromServiceAsync(string url, string login, string password)
  {
       Debug.WriteLine("[" + DateTime.Now + "] GetDataFromServiceAsync");
       var handler = new HttpClientHandler { Credentials = new NetworkCredential(login, password)/*, UseProxy = false*/ };
       var client = new HttpClient(handler) { MaxResponseContentBufferSize = Int32.MaxValue };
       try
       {
           var resp = await client.GetAsync(new Uri(url));
           var content = resp.Content.ReadAsStringAsync().Result;
           var auth = ParseContent(content);
           Debug.WriteLine("[" + DateTime.Now + "] Returning AuthResult : " + auth);
           return new AuthResult { Success = auth, Exception = null};
       }
       catch (Exception exception)
       {
           //
           Debug.WriteLine("[" + DateTime.Now + "] Returning error AuthResult : " + exception.Message);
           return new AuthResult { Success = false, Exception = exception }; ;
           }
       }
  }
  </code></pre>
  
  <p>This method is wrapped with other method from api that actually does nothing relevant to current case :</p>
  
  <pre><code>public async Task&lt;AuthResult&gt; IsAuthenticated(string login, string password)
  {
      Debug.WriteLine("[" + DateTime.Now + "] Starting ISAuthenticationService.IsAuthenticated");
      // ... (cut) ...
      // async
      var authResult = await ISHelpers.GetDataFromServiceAsync(url, login, password);
      Debug.WriteLine("[" + DateTime.Now + "] Ending ISAuthenticationService.IsAuthenticated");
      return authResult;
  }
  </code></pre>
  
  <p>Authentication happens in respective ViewModel command :</p>
  
  <pre><code>private async void ExecuteAuthenticationCommand()
  {
      // Test stub
      //var authService = new Helpers.MockupAuthenticationService();
      var authService = new Helpers.ISAuthenticationService();
      var auth = await authService.IsAuthenticated(Login, Password);
      if (auth.Success)
      {
          MessageBox.Show("Authentication success");
          Messenger.Default.Send&lt;LoginDataItem&gt;(_dataItem);
      }
      else
      {
          MessageBox.Show(auth.Exception.Message, "Incorrect login data");
      }
   }
  </code></pre>
  
  <p>Debug output :</p>
  
  <pre><code>[27.06.2012 16:54:10] Starting ISAuthenticationService.IsAuthenticated
  [27.06.2012 16:54:10] GetDataFromServiceAsync
  [27.06.2012 16:54:25] ParseContent in GetDataFromServiceAsync
  [27.06.2012 16:54:25] Returning AuthResult : True
  [27.06.2012 16:54:25] Ending ISAuthenticationService.IsAuthenticated
  </code></pre>
  
  <p>When i uncomment UseProxy = false in HttpClientHandler settings, latency passes away and auth has no delay. Problem is same happens sometimes even when i don't uncomment UseProxy (one run per about dozen runs). The question is - is that a bug or what? Tried to debug that from server-side, no differences between polling requests found. Thanks in advance.</p>