We use the DFP-small business platform to serve adsense with GPT (Google Publisher Tag) async in single request mode. The new GPT tag loads the ads in async and reduces the number of http. That said, the ads are always the last elements on the page to be visualized. We’ve determined that its neither a traditional loading or rendering problem but rather a slow loading of the iframe content. The latency is greatest on Safari (mac) and ie9 and oftentimes the ads are visualized several seconds after the next to last item visualized.

We’ve tested the page in firebug, pingdom, webpagetest and google console.

All show that the adds load when called and render properly, they aren’t blocking the onload event, nor is an other element blocking the onload event or any other element.

We’ve tried placing the GPT tags at the top of the page, calling the GPT js in the header, setting a timeout for both the header and body, loading everything else but our html and css files after the onload event.

In all cases, ads loaded with GPT tags in async and single reguest mode are the last items visualized on the page.