title: windows.postMessage behaviour?
body: <p>I need a cross domain call for sending a data to another server and get back same data to validate it, so for that I used window.postMessage with Iframe. </p>
  
  <p>Its working fine. </p>
  
  <p>I am sending a 1 MB string in message and get back from, so it is sending 1 MB string and receiving 1 MB string, this task completes in appx 4 SECs. I think this will not happens. </p>
  
  <p>But When I used jsonp to download the same contents from same server using ajax jsonp, it takes 9 seconds.</p>
  
  <p>So finally download only takes 9 secs and postmessage (send &amp; response)  both takes 4 secs. How it possible ? I think its should be more than 9 seconds. </p>
  
  <p>Please let me know why it happens.</p>
  
  <p>Thanks,
  Laxmilal Menaria</p>