Ads requested through via doubleclick often get served from an ad provider network that returns javascript that in turn performs document.write to place ads in the page. The use of document.write requires that the document be open, implying that the page hasn't reached document.complete. This gets in the way of deferring or lazy loading ad content. Putting such code at page bottom is helpful but doesn't do enough to lower all-important "page-loaded" time. Are "friendly iframes" the best we have? Is there any other alternative such as a clever way to override document.write?