title: Why callback from wcf service is so slow (especially the first time)
body: <p>I have a service that sends several callbacks per second to connected clients. Why when the service sends a message do the clients get them a few or more seconds later?</p>
  
  <p>Here are the configuration details:</p>
  
  <pre><code>        &lt;bindings&gt;
                    &lt;wsDualHttpBinding&gt;
                      &lt;binding name="WSDualHttpBinding_IMyService" receiveTimeout="00:30:00" 
      sendTimeout="00:30:00" useDefaultWebProxy="false" maxBufferPoolSize="2147483647" 
  maxReceivedMessageSize="2147483647"&gt;
  
                        &lt;readerQuotas maxDepth="2147483647" maxStringContentLength="2147483647" 
          maxArrayLength="2147483647" maxBytesPerRead="2147483647" maxNameTableCharCount="2147483647" /&gt;
                        &lt;security mode="None"/&gt;
                      &lt;/binding&gt;
                    &lt;/wsDualHttpBinding&gt;
                  &lt;/bindings&gt;
                  &lt;behaviors&gt;
                    &lt;serviceBehaviors&gt;
                      &lt;behavior name="Service1Behavior"&gt;
                        &lt;serviceMetadata httpGetEnabled="True"/&gt;
                        &lt;serviceDebug includeExceptionDetailInFaults="True"/&gt;
                        &lt;serviceThrottling maxConcurrentCalls="10"
                                  maxConcurrentInstances="10"
                                  maxConcurrentSessions="5" /&gt;
                      &lt;/behavior&gt;
                    &lt;/serviceBehaviors&gt;
                  &lt;/behaviors&gt;
  </code></pre>