title: How to trace overhead added by Application Request Routing?
body: <p>We have a Delphi SOAP service which needs to be SSL-enabled.  I opted to use an IIS ARR reverse proxy to do SSL offloading for ease of configuration (compared to OpenSSL and manual certificate + passphrase management).  ARR works, but it adds an insane amount of overhead...  Response time went from <strong>under 2 seconds to 19 seconds</strong> for 18 service requests (about 60Kb compressed total).</p>
  
  <p>I added timestamp logging to client &amp; server for when messages are both sent and received.  It shows about 1 second added to each request routing through ARR between sending from the client and receipt by the service.  The response is routed back very quickly, only the request routing via ARR is slow (see image below).</p>
  
  <p>How can I trace the source of overhead?  Is ARR not suited to this use case?  I tried tweaking and disabling most settings, including caching.  I tried different hosts with clean IIS setups, including a production Windows Server 2012.  SSL itself is not the overhead, just having an ARR HTTP reverse proxy causes the delay.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;configuration&gt;
      &lt;system.webServer&gt;
          &lt;rewrite&gt;
              &lt;rules&gt;
                  &lt;rule name="ReverseProxyInboundRule1" stopProcessing="true"&gt;
                      &lt;match url="(.*)" /&gt;
                      &lt;action type="Rewrite" url="http://localhost:8987/{R:1}" /&gt;
                  &lt;/rule&gt;
              &lt;/rules&gt;
          &lt;/rewrite&gt;
      &lt;/system.webServer&gt;
  &lt;/configuration&gt;
  </code></pre>
  
  <p>Request &amp; response samples from Fiddler:</p>
  
  <ul>
  <li><a href="https://drive.google.com/file/d/0BzULbx5Yjhv-M3R4TVdHUW5PVDA/edit?usp=sharing" rel="noreferrer" title="Raw HTTP Request">Raw HTTP Request</a></li>
  <li><a href="https://drive.google.com/file/d/0BzULbx5Yjhv-Y1MzTWhXWU1kbk0/edit?usp=sharing" rel="noreferrer" title="Raw HTTP Response">Raw HTTP Response</a></li>
  </ul>
  
  <p><img src="https://i.stack.imgur.com/rk4H3.png" alt="Client and server timestamps grid"></p>
  
  <p><img src="https://i.stack.imgur.com/Nh0yW.png" alt="I0IS Tracing shows overhead from ARR"></p>