Lazy loading – a valuable solution for your advertising business?

Lazy loading, a pretty common term in the world of programming has been recently gaining traction also in digital advertising. Given its popularity, we would like to discuss the real impact of this approach on publishers programmatic revenues.

What is lazy loading?

Let’s begin with the definition. Lazy loading is nothing else than a mechanism that delays the process of ad rendering, so users are more likely to actually see an ad. The exact moment is defined in an ad script and it is the number of pixels between the bottom of the page and ad unit location. Usually, the shorter this distance the higher the ad viewability as the chance that a user will get to the ad unit and see the ad is higher.

While higher viewability is certainly the main advantage of lazy loading, there is also another important benefit. Namely, as only limited number of ads render at a given point in time, not all of them, it has a positive influence on a page load time. It also translates to a better user experience.


The concept of viewability belongs to the most important ones in digital advertising. According to IAB, an ad can be considered viewable if at least of 50% of it is surface pops up in a visible part of the browser for one second or more. For video ads IAB suggests it should be 50% of ad surface for at least 2 seconds.

Based on Meetrics Benchmark Report for Q3 2019, the average international viewability is 58% for display ads and 83% for video ads. While video certainly does better than display, which can be attributed to the location of video placements, it is worth mentioning that desktop display ads are significantly more viewable than mobile ads. So, while there is a room for improvement in terms of display ads viewability, it is exceptionally big for mobile.

Lazy loading and programmatic revenues

Advertisers do not want to purchase non-visible or poorly visible ads anymore. Given that, lazy loading should lead to an increase in demand for such inventory, as buyers would theoretically be more likely to pay more for more viewable ad impressions. On the other hand, properly implemented lazy loading makes the number of ad requests decrease. Not all users reach the bottom of the page, which means not all ad units will be called, which means there will eventually be less ad impressions compared to standard eager loading.

When it comes to open auction, the results may vary. The interplay between higher CPMs and lower number of ad impressions does not always benefit publishers. The outcome is often positive, but to be frank, in some cases we noticed drops in total open auction revenues, which lead to a conclusion, that lazy loading is not a simple plug & play solution. A publisher should definitely run some A/B tests and add some analytics in order to find out, where lazy loading works and where it does not, as well as its most optimal setup.

The situation looks different in terms of private marketplace and direct deals, though. When a publisher cherry picks highly viewable, lazy loading ad units and package them, they can ask a higher price with no losses on the volume of ad impressions. The remaining traffic might be left to open auction without lazy loading or limited lazy loading or any scenario optimizing this programmatic channel.

This approach can be easily adopted in traditional direct campaigns as well as guaranteed deals. It may lead to higher margin on highly viewable inventory, but only when it does not put the number of ad requests at risk.

To wrap-up

Lazy loading is all about loading ad units only when a user is likely to actually see the ads. The core benefits of this mechanism is an uplift in ad viewability, but may cause some drops in the number of ad requests and hence ad impressions. It is especially worth trying in terms of PMPs and direct deals, but can also be used for open auction as long as it is preceded by A/B tests and analytics.

Want to know more about lazy loading and other interesting solutions for your programmatic business?
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