I've question: is there a way to load the entire page before the iframe? and then if the iframe content takes time to load, it doesnt delay the loading of the rest of the page?
Thanks in advance for your advice.
an iframe uses the same resources as it's parent. That includes connection limitations (3 scripts at a time, etc.), DOM painting, and, of course, the thread used to parse javascript code.
It is recommended to start loading (maybe even building) an iframe after your main page has finished loading. You can get the onload event from the iframe, but if you have control over it's content I prefer using a postMessage for DOMContentLoad event to be sure.