title: High latencies loading stores in an ExtJS 4.1 MVC application
body: <p>I'm currently working to turn a web app made with a homemade interface library into a standard ExtJS MVC application. Everything works fine except Ajax requests which suffer higher latencies on page startup. Indeed, although the file I call is not really different than before, sometimes I have to wait from 3 to 6 seconds more than before to get the response back. </p>
  
  <p>To reduce the scope of my investigations, I have changed the code to return static data (a simple json string), eliminating the option of a database issue. Moreover, I have noticed that using "Replay XHR" in Google Chrome ("Network" panel) I get the response back almost instantaneously.</p>
  
  <p>I guess it's hard to help on this topic but hope someone has already encountered this kind of issue and could share some advices on where to investigate.</p>
  
  <h2>Observations</h2>
  
  <ul>
  <li><p>requests sorted by latency (the gap is about 500ms) :</p>
  
  <p><img src="https://i.stack.imgur.com/Ibevj.png" alt="enter image description here"></p></li>
  <li><p>requests sorted by start time :</p>
  
  <p><img src="https://i.stack.imgur.com/UxK2H.png" alt="enter image description here"></p></li>
  </ul>