title: Azure Iot Hub FeedbackReceiver ReceiveAsync is very slow (15 seconds) high latency
body: <p>if I send a message (Cloud 2 Device) via the IoT-Hub:</p>
  
  <pre><code>var serviceMessage= new Message(Encoding.ASCII.GetBytes("Hello Device"));
  serviceMessage.Ack = DeliveryAcknowledgement.Full;
  commandMessage.MessageId = Guid.NewGuid().ToString();
  await serviceClient.SendAsync("myDeviceID", serviceMessage);  //Send message here
  </code></pre>
  
  <p>And try to receive the acknoledgement from the client:</p>
  
  <pre><code>bool feedbackReceived = false;
  while(!feedbackReceived){
    FeedbackReceiver&lt;FeedbackBatch&gt; feedbackReceiver = serviceClient.GetFeedbackReceiver();
    var feedbackBatch = await feedbackReceiver.ReceiveAsync(TimeSpan.FromSeconds(1));
    if(feedbackBatch != null)
      {
        feedbackReceived = feedbackBatch.Records.Any(fm =&gt; fm.OriginalMessageId == serviceMessage.MessageId);
        if (feedbackReceived)
          {
            await feedbackReceiver.CompleteAsync(feedbackBatch);
            feedbackReceiver = null;
          }
      }
  }
  </code></pre>
  
  <p>My client gets the message immediatelly and sends an feedback:</p>
  
  <pre><code>DeviceClient deviceClient = DeviceClient.Create(iotHubUri, new DeviceAuthenticationWithRegistrySymmetricKey(bridgeID, deviceKey), TransportType.Amqp);
  Message receivedMessage = await deviceClient.ReceiveAsync();
  await deviceClient.CompleteAsync(receivedMessage);
  </code></pre>
  
  <p>It take up to 15 seconds until my Cloud gets the feedback.
  If I send messages in a loop, then the first message needs something between 1 and 15 sconds and every following response needs exactly 15 seconds.</p>
  
  <p>Why does that need so long? Can I change it?
  The receive-method in my cloud gets an answer immediatelly:</p>
  
  <pre><code>var incommingMessage = eventHubReceiver.ReceiveAsync();
  incommingMessage.Wait();
  </code></pre>
  
  <p>If the client sends a message:</p>
  
  <pre><code>var message = new Message(Encoding.ASCII.GetBytes("My Message"));
  await deviceClient.SendEventAsync(message);
  </code></pre>
  
  <p>A whole project with the problem is on gitHub:
  <a href="https://github.com/Ben4485/Azure_IotHub_Get_Response" rel="nofollow">https://github.com/Ben4485/Azure_IotHub_Get_Response</a></p>