title: Does iframe runs on the same thread as the owner?
body: <p>I have a CPU intensive work to do and i don't want to degrade the user experience. since web workers (<a href="http://ejohn.org/blog/web-workers/" rel="noreferrer">http://ejohn.org/blog/web-workers/</a>) are a new feature and are not supported by all browsers, i thought to open an iframe with an HTML + JS that will do all the dirty work and using some cross-domain communications to pass on the results. 
  Unfortunately i noticed that the owner of the iframe suffers from the CPU work of the iframe window. </p>
  
  <p>Does this behavior is as designed? is there a way to solve this?</p>