title: NServiceBus 4.0.4 Subscriber very slow
body: <p>I have a problem with my publish/subscribe implementation. I'm upgrading from NServiceBus version 2.6 to 4.0.4 and everything seems okay as far as I can understand from the logs but the messages are processed really slowly by the subscriber. I use NServiceBus.Host.exe.</p>
  
  <p>In the old implementation I have configured threads as follows:</p>
  
  <pre><code>&lt;MsmqTransportConfig 
     ErrorQueue="error" 
     NumberOfWorkerThreads="40" 
     MaxRetries="5" /&gt;
  </code></pre>
  
  <p>And the messages go through with nice speed.</p>
  
  <p>In the new implementation I've tried to make the changes needed for the configurations:</p>
  
  <pre><code>&lt;TransportConfig
      MaximumConcurrencyLevel="10"
      MaxRetries="5"
      MaximumMessageThroughputPerSecond="500"/&gt;
  </code></pre>
  
  <p>Am I missing something critical?</p>
  
  <p>I have a valid license so I should have max threads in use. I haven't got RavenDB or SQL, the implementation uses MSMQ, I've disabled Sagas and TimeoutManager in my subscribers configuration code:</p>
  
  <pre><code>NServiceBus.SetLoggingLibrary.Log4Net(log4net.Config.XmlConfigurator.Configure);
  Configure.Features.Disable&lt;Sagas&gt;();
  
  NServiceBus.Configure.With()
     .DefaultBuilder()
     .UseTransport&lt;Msmq&gt;()
     .DisableTimeoutManager()
     .UnicastBus()
     .LoadMessageHandlers(); 
  </code></pre>
  
  <p>I did a crude test and the difference in my development environment is so that the 2.6 version handled approximately 80 messages per second and the 4.0.4 version handled approximately 8 messages per second - which is really very bad. So something's wrong here and I just can't seem to find what it is.</p>
  
  <p>Edit: It looks like the problem was generated from our project structure, for some reason the older version of NServiceBus didn't mind our structural approach with generic subsrcriber that uses MEF to load the actual subsrciber-assemblies but the new one went to sleep. I changed the folder structure and now the subscriber works as intended. So the configurations I was using work just fine, but I did delete MaximumMessageThroughputPerSecond from my settings so that it won't present a future problem since the aim is to be as fast as is possible.</p>