Lazy Loading: Benefits and drawbacks

As a publisher, you’re always looking for methods to improve your site’s performance, whether it’s in terms of monetization, layout, or user experience. You may have heard other publishers discuss “Lazy Loading” or “Ad Refresh” and how it has helped them reach their objectives.
What works for one publisher’s website may not work for another. In this piece, we will look into lazy loading ads to help you determine whether it’s worth it to implement them.

Lazy loading

So, what is Lazy Loading?

When a visitor accesses a web page, all of its contents are typically rendered and downloaded in a single instance. The browser can cache the web page, but this does not always imply that people will be able to access it completely.

Pages with lazy loading ads are prepared using placeholder content or empty containers that are replaced with genuine content only when the user scrolls down to it. In short, webpage material is loaded only when it is visible on the user’s screen.

When implemented correctly, the primary benefit of lazy loading is reduced bandwidth utilization. In an image gallery, for example, instead of loading all images, just those that are likely to be viewed are loaded.
It does, however, entail dangers, hazards, and trade-offs.

Publishers should not assume that lazy load is better for their audience because those who try it typically experience varied results.

Some businesses have gone through hundreds of implementations before settling on a single version that enhances user engagement or other KPIs. Typically, publishers attempt to maximize effective pageviews per session, ad income per session, or a combination of the two.

Where can you apply lazy loading?

On a per-unit basis, lazy loading can be used. It is ideal to use lazy loading for ads that appear below the fold because it reduces latency and CPU consumption. Above-the-fold ads are already in the users’ viewport, therefore they do not need to be lazy-loaded.

The key benefits of lazy loading ads

  • Better user experience

Ads can be resource-intensive, and publishers are all too aware of the impact of having too many ads on the page on speed and performance. In two ways, lazy loading can help with this: For starters, the number of ad requests can be minimized because ads are only loaded if they are likely to be watched. It saves processing time and bandwidth that would have been used on an unseen impression.

Lazy loading, in addition to reducing total load, can improve the feeling of speed. Because the “delayed” adverts are not required on the initial page load, resources are freed up to load and render the primary content. This speeds up the page’s loading time, with the advertising being called after the content is safely on-page. Fast loading pages are also advantageous for SEO because Google’s ranking system favors pages with lower load times.

Ads that are unlikely to be noticed are not loaded using lazy loading, resulting in fewer unviewed impressions being served. This has the potential to significantly increase your viewability scores. Advertisers despise paying for impressions that their customers do not see, therefore the greater your viewability score, the more desirable your inventory is to those booking high-priced campaigns.

Viewable impressions are frequently used by advertisers as a campaign KPI, demonstrating more accurately that a user has seen an ad — this can also convert into higher click-through rates. Advertisers will frequently avoid poor viewability inventory outright, and some SSPs will only pay for watched impressions.

  • Increased revenue

Implementing lazy loading ads will often result in more income for publishers over time. This is due to the fact that lazy loading will only cause the advertising to load when a user intends to view them. As a result, your general viewability will improve, increasing the value of your inventory and leading to more competitive auctions and higher rates over time.


Lazy loading appears to be a simple approach to boost both the user experience and revenue in one fell swoop. Unfortunately, it is not as simple as that. Available inventory may suffer as a result of lazy loading, which only renders advertising when necessary, reducing the number of ad requests made to the ad server and the overall number of impressions given.

When publishers are paid on a CPM basis, this can have a negative impact on revenues at first. Even if the impressions with the lowest CPM are not served, slow loading reduces the amount of impressions. Because the effects of higher-value inventory are not immediate, most publishers will experience a short-term revenue reduction when they employ lazy loading.

Another disadvantage of lazy loading advertising is that split testing is difficult. This is because ad viewability increases with time, and advertisers will not bid higher until it does. As a result, conducting such tests is not particularly beneficial because you are unlikely to notice any immediate income increases.

Furthermore, while most advertisers consider ad viewability when developing a campaign, if it is not a key performance indicator (KPI), it is doubtful that they will pay exclusively for viewable impressions. In such an instance, you’d be allowing your revenue to suffer as a result of impressions that purchasers were not unsatisfied with.

Another typical stumbling block is the potential negative influence on a website’s search engine ranking. Lazy-loaded content is frequently overlooked by search engines. Because the resource defaults to placeholder content, a search engine crawler is likely to misread or ignore its contents. As a result, the lazy-loaded component may be bypassed, resulting in fewer search engine results.

For these reasons, we strongly suggest publishers interested in lazy loading to do an A/B test first to evaluate if its implementation increases effective pageviews per session. Once that milestone is met, the publisher can begin experimenting with revenue optimizations.

Final thoughts

To sum it up, lazy loading postpones the rendering process until users are likely to encounter advertisements. Typically, this is accomplished by only initiating ad requests when a user scrolls to a specific position on a page near the ad itself.

Publishers who sell inventory through PMPs and direct transactions stand to benefit the most because purchasers tend to cherry-pick high viewability ad units. This enables publishers to bundle their content and sell it at higher rates, mitigating the losses caused by lower impressions.