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Google is making good on promises it made to speed its AdSense code, rolling out an overhaul aimed at relieving the drag on publishers’ Web pages.

The company estimates that its helping pages load faster by a half a second or more, when, previously, Google acknowledged that its code could delay page loads by 12 percent on average. Besides helping user experience, the change may help AdSense sites rank better for search, since Google uses site load times as one signal.

The change happens automatically, without publishers having to change the code placed on their pages.

In the old implementation, the AdSense javascript would load additional scripts, gather information from the web page where it resided, and send an ad request back to Google. Now, the code — without publishers making any changes — will start by creating an iFrame on the publisher’s Web site. That isolates the AdSense code from everything else that’s happening on the page, allowing the rest of the page to load without having to wait for the Google code to do its thing.

“[The first script's] main job is to call the actual implementation of the AdSense script and then give back the control to the browser, so the web page can continue loading in parallel,” Richard Rabbat, the product manager at Google who led the charge, told me.

Google’s testing on the new code showed that pages with AdSense now load as quickly as they would with no ads at all. The change won’t be as dramatic on sites whose pages consist of a lot of AdSense ads, and those who have already implemented their own iFrame solutions won’t see much of an impact, either.

Currently, the change is occurring globally on Google Chrome, Mozilla Firefox and Microsoft Internet Explorer 8. The company hopes to expand the list of supported browsers soon.

The roll-out is something that Google talked about at the Velocity conference nearly a year ago, and it’s spent the intervening months making sure that it would work well and easily, without publishers having to make changes. More than 2 million publishers are using Google AdSense.

“We spent a lot of time making sure that this technique works very well,” said Rabbat, “We have dealt with a lot of corner cases.”

Related Topics: Channel: Display | Google: AdSense

About The Author: Pamela Parker is a contributing editor for Search Engine Land and Executive Features Editor at Marketing Land. She’s a well-respected authority on digital marketing, having reported and written on the subject since 1998, including a stint as managing editor of ClickZ. She’s also worked to help monetize independent publishers’ sites at Federated Media Publishing. She blogs about media and marketing at The River and about cooking, gardening and parenthood at Free Range. She can be found on Twitter as @pamelaparker. See more articles by Pamela Parker

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