Does Lazy Loading Ads Solve the Viewability Problem?

What Does Lazy Loading Ads Mean?

Traditionally in web design, a browser calls a web server, which returns all the HTML necessary to render the entire page to the browser in a source code file.  Now that file may contain redirects and references to other web servers that the browser has to call in order to fully render the page, but the general idea has been that browser fully loads the whole page for the user as quickly as possible.  Such that, if the page is extremely long, contains lots of images, or what have you, the whole thing is rendered at once, irrespective of the user’s navigation.  In other words, the browser renders everything, whether the user ever views that content or not.

“Lazy loading” (sometimes also known as “just-in-time loading” on the other hand, is a relatively new method of web design that renders the page on an as-needed basis, just as the user is scrolling their browser down to that piece of content.  If you’ve seen pages that contain an “infinite scroll” design, you have the general sense.  The content available to the user isn’t all loaded at once, because it would take forever; rather, the page renders as you the user scroll to it.  If you don’t scroll down, the content isn’t rendered.  So lazy loading any web content, ads included means the web server only provides the necessary source code to the browser as the user needs it.

The Performance Benefits of Lazy Loading Ads

Lazy loading advertising content in general has a few benefits; first, your page performance from a latency and time to load perspective typically improves because you are reducing the amount of data a browser has to download.  Holding network speed constant, the best way to make pages load faster is to make them lighter.  Loading content as a user needs it accomplishes that nicely, and as advertisements are especially heavy because they are 3rd party hosted images, lazy loading ads tends to have an outsized impact on performance.

In fact, the New York Times recently switched their site design over to lazy loading content, and called out advertisements in particular in a blog post about the strategy.  In the article, the Times mentions they achieved a 50% improvement in page performance, largely because their lazy loading strategy (that also relies on writing the ad into a dedicated iFrame on the page) prevents the JavaScript code many ads require from running in-line to the rest of the page content, and thereby holding up the over render time.

How Lazy Loading Addresses Viewability

Aside from the performance benefits of lazy loading ad content though is the happy consequence that every ad view is also visible to the user, since the content is only rendered when the user is scrolling the content into view.  While it’s true there’s still a lingering debate over how viewability is measured – this Digiday post gives a good overview on the complexities of each viewability vendor using different methodologies to measure the same MRC standard (50% of the ad content in-view for at least one second) – there’s no question that a lazy loading strategy is far superior to traditional content rendering in terms of ensuring your ad requests are viewable.

Now, rendering the ads as they slide into a user’s active view isn’t going to help publishers cope with the reduction in inventory – in fact, it may even be jumping the gun.  After all, the industry hasn’t yet shifted to a standard that requires publishers bill off a viewable metric, though most publishers are seeing soft requirements (meaning they’ll be measured and evaluated against others based on viewability) for it on the majority of RFPs now.  My guess is it’ll be perhaps two years before it becomes a billable standard in the IAB / 4A’s standard T&Cs, though I’ve been surprised how fast this issue has moved already.

I’ve thought for awhile now that viewability actually isn’t a positive thing for the industry and that it will have the unintended consequence of promoting lower quality content and ad layouts.  If publishers are forced to bill off viewable impressions, then my hypothesis has been that publishers will reconfigure their pages to ensure every ad is viewable, which will probably mean the pages will get worse.  For example, I suspect we’ll see even more slideshow-style content or highly paginated content where everything on the page can load in-view, as well as very cluttered and lower quality ad placement above the fold on articles.  These ads will be in view, but will it make for an overall better ad experience for users and advertisers, I tend to think not.  Lazy loading ads however might be somewhat of a compromise.  Publisher could keep user-friendly page layouts and not worry as much about 3rd party viewability measurement, though they’ll still lose inventory relative to what they have today.   One voice that makes a lot of sense on this topic is Josh Schwartz‘s over at Chartbeat, who notes that the more engaging the content, the higher the viewability score for the ads.

Implementing Lazy Loading Ads

There are a few ways to implement lazy loading ads, and most of them are free and open source on Github if you are comfortable with some development work.  One popular solution is the PostScribe library from the kind folks at Krux (usually just part of an overall solution), which the Times references in their post.  Other libraries are also out there, such as jQuery.dfp.js, jQuery LazyLoad Ad, and Lazy Ads, though none other backed by an ad tech company, so you’d want to have the resources in house to support those solutions yourself.

And finally, it seems possible to implement lazy loading ads with DoubleClick’s GPT tags in an SRA (Single-Request-Architecture) configuration as Mike McLeod notes on this AdMonsters Forum post.