<b>Lazy-load ads with a tuned rootMargin</b>

<b>Lazy-load ads with a tuned rootMargin</b>

What it does: defers ad calls until the slot nears the viewport, using IntersectionObserver. The lever nobody tunes is rootMargin.

Setup effort: 2/5 — most ad managers (GPT, Ezoic, AdThrive) expose a fetchMargin or lazy threshold.

RPM lift seen: viewability jumps from ~45% to 65-70%, which drags up CPMs on viewable-buy demand. But total impressions drop, so net RPM moves +6 to +12% on long scrollers, near zero on short pages.

Pros
— Higher viewability = better demand quality
— Less wasted ad load below the fold

Cons
— Set margin too tight (0px) and fast scrollers see blanks
— Adds latency to first paint of the unit

Verdict: tune to ~300-400px fetch margin, not 0. Lift: ★★★★☆ — Risk: ★★☆☆☆
Best for: long-form/listicle sites. Skip if your pages are short and above-fold heavy.