I have a web page with many iFrames, thus i did a speed test on webpagetest.org and had the result show. Each line in the graph is an iframe. As the document complete blue line is far behind, can i say these iFrames are hindering the page load? After some research i think if i am not wrong, if i implement asynchronous loading of the iFrame, the loading of iframe pages will only after the document load finish.
Not sure exactly what the question is but yes, the load event of the main document is blocked until the load event for all of the iframes has also fired (i.e. all of the contents of all of the iframes have loaded).
Phillip Tellis had an article on how to create iframes that do not block the document load event (basically create an empty iframe and then in the load event handler inject the actual contents) : http://calendar.perfplanet.com/2012/the-non-blocking-script-loader-pattern/