title: WCF (.NET 4.0) long delay in AuthenticateRequest state in IIS
body: <p>We have a set of WCF (.NET 4.0) services hosted in IIS7. We recently observed strange behaviour on production:</p>
  
  <p>In IIS7 we opened the 'Current requests in the worker process' view for one of them (the most often called) and noticed that many request are 
  listed in AuthenticateRequest state (ModuleName = ServiceModel-4.0) with time elapsed reaching up to a few seconds and then they disappear.
  We don't really use any authentication in this service.</p>
  
  <p>AuthenticateRequest is a very early stage in the pipeline and we're wondering what could be holding them up there?
  We tried increasing the maxConcurrentCalls limit but that didn't seem to have any effect.</p>
  
  <ul>
  <li>Is this abnormal behaviour? </li>
  <li>I assume our application code has not been executed at this stage, yet, is this correct?</li>
  <li>If this is a contention of some sort what could be the problematic resource? We have mutliple WCF services running on that machine.</li>
  </ul>
  
  <p>Thanks,
  Piotr</p>