Lazy Loading Ads: Benefits, Risks and Setup Tips

Lazy loading is a technique that delays loading an element until it is about to enter the screen. Many sites already lazy-load images. Applying the same idea to ads can make pages faster and improve the quality of your impressions.

How it works

Instead of requesting every ad when the page first loads, the page watches the reader’s scroll position. When an ad slot comes within a certain distance of the visible area, often one or two screen heights, the ad request is sent. By the time the reader reaches the slot, the ad has usually loaded.

The benefits

• Faster first view: fewer requests compete with your main content when the page opens.
• Higher viewability: impressions are counted only when readers are actually near the ad.
• Better data: your impression and viewability numbers reflect real reading behavior.
• Less wasted demand: advertisers do not pay for ads at the bottom of pages that most visitors never reach.

The risks

• Fewer impressions: if many readers leave early, lower ads never load. Total impressions can fall even though each one is more valuable.
• Late loading: if the trigger distance is too short, readers may scroll past an empty slot.
• Layout shift: slots that expand when an ad arrives can make the page jump if space is not reserved.

Setup tips

1. Do not lazy-load the first ad. The unit near the top should load immediately.
2. Choose a sensible distance. Start by loading ads about one to two viewport heights before they appear, then adjust based on results.
3. Reserve space. Give each slot a minimum height so content does not jump.
4. Use your network’s built-in option where available. Google Publisher Tag, for example, has a lazy-load setting, and many ad management plugins include it.
5. Test on mobile. Fast scrolling on phones can outrun ad loading if the distance is too short.

Measuring the result

Compare a few weeks before and after the change. Look at page RPM, viewability, total impressions and Core Web Vitals. A successful setup usually shows slightly fewer impressions, higher viewability, similar or better RPM, and faster pages.

Is it worth it?

For long articles with several ad units, lazy loading is usually a good idea. For short pages with one or two ads, the benefit is smaller. As with every optimization, measure rather than assume, and keep the reader’s experience at the center of your decisions.