Lazy loading isn’t simply “don’t load ads until users scroll near them”. There are multiple ways to control how and when ads load, and each choice has a real impact on viewability, user experience, and revenue.
In this article, we are sharing our guidelines and comparing lazy loading through Google Ad Manager (GAM) and lazy loading through a third-party ad tech platform like Relevant Yield. Pick whichever fits your stack, as long as you set things up correctly.
Why Lazy Loading Is Needed
Without lazy loading, every ad on the page loads immediately, including all the below-the-fold placements users may never reach.
- Slower page performance
- Low viewability for lower placements
- Wasted impressions
- Lost revenue due to poor viewability scores
When Should Lazy Loading Trigger?
Viewability improves not because the ad magically becomes viewable, but because you stop logging impressions that users never had a chance to see.
Most publishers land around 200 - 500px above the fold as the preload threshold. This buffer gives the ad enough time to:
- Run header bidding
- Fetch the creative
- Render before the user arrives
Key Lazy Loading Settings Publishers Need to Optimise
1. Trigger distance (viewport offset)
This is the distance from the viewport where the ad request fires. Test different offsets to avoid late rendering or unnecessarily early auctions.
2. Preload behaviour (including GAM prefetch)
Some setups allow you to prefetch the creative. This means the creative loads earlier and is instantly ready when the slot triggers.
GAM’s lazy loading includes a prefetch function, which is useful as it reduces the risk of blank slots and protects fast scrollers.
But prefetch isn’t the only solution.
Smart offset tuning + lightweight creatives + stable bidding can deliver the same end result.
For publishers with complex setups, granular placement-level control often matters more than prefetching alone.
3. Per-placement configuration
This is the part where many publisher workflows fall apart.
- Some placements need aggressive lazy loading.
- Others (premium or highly viewable inventory) need conservative settings.
- Mobile, infinite scroll, sidebars, sticky units all behave differently.
GAM’s lazy loading only gives two buckets: desktop and mobile, which is quite limiting for complex inventories.
Working with publishers of all sizes, we saw this immediately. Relevant Yield’s lazy loading was built to fix this: every placement can have its own lazy loading settings. Hero units, mid-article boxes, and infinite scroll are all configurable.
And because we’re tech-neutral, you can also enable GAM lazy loading through Relevant Yield.
Recommended Lazy Loading Strategy for Modern Publishers
Here’s a practical lazy loading guideline from Relevant Digital’s programmatic team:
1. Start with a baseline offset
300px above the viewport, then adjust based on performance.
2. Prioritise high-value placements
Hero units or premium positions may require a slightly earlier trigger to avoid risking delayed impressions.
3. Be more aggressive deep down the page
Below-the-fold units often benefit the most from lazy loading. Don’t be afraid to push the trigger lower. The traffic quality improves dramatically.
4. Test your theories & track performance
Take advantage of real-time header bidding analytics and daily revenue data to correctly measure:
- Viewability uplift
- CTR changes
- Bidding latency
- Potential revenue impact
- Time-to-render
Constantly test different lazy loading settings and monitor them closely to find the optimal lazy distance. Another “work smart” trick is to get yourself an alarm system to ping you whenever anomalies occur!
5. Keep user experience in mind
Try scrolling on your pages and fairly judge your experience. Heck, get your friends and family to experience your pages. We are, in the end, all internet users who get icked by bad ads. 😉
Make sure your work gives a pleasant user experience. If lazy loading causes layout jumps or visible rendering delays, you’ve gone too far.
Fix What You Load, Not Just When
Lazy loading is one of the simplest and most overlooked levers publishers have. It cuts waste and improves UX, if done right, just like everything else.
The publishers who are successful with lazy loading make sure to do these things:
- Tune thresholds
- Optimise per placement
- Use performance data to refine
- And align lazy loading with their broader monetisation strategy.