I’ve been thinking a lot about lazy-loading recently.
Because once you see how often it’s misused (or not used at all) it’s hard to unsee. From plummeting SEO rankings to painfully slow product pages that quietly murder conversions, lazy-loading is like flossing for e-commerce: everyone knows they should do it, but few do it well.
And in 2025, there’s no excuse.
The promise of lazy-loading
In theory, lazy-loading is a beautiful thing.
Why load a 1MB product image the moment someone opens a category page, when you could wait until they’re about to scroll to it? Why force every third-party script to execute up front, when it could defer until it’s truly needed?
Done right, lazy-loading speeds up first paint, improves core web vitals, and keeps customers happy – and Google even happier.
But in practice? It’s a graveyard of broken assumptions and performance potholes.
The hidden cost of lazy-loading mistakes
Most devs treat lazy-loading like a performance checkbox, not a UX investment.
Here’s what that gets you:
- Lazy-loaded hero images. Your main banner or product shot takes a full second to appear. Looks broken. Feels broken. Users bounce.
- Images set to
loading= "lazy"but never seen. Because of carousels, tabs, or other JS interactivity. Google can’t crawl what it can’t see. - JS-heavy lazy-loading with no graceful fallback. Your $300 sneakers never load if the JS fails – or loads too late.
- Lazy-loaded LCP elements. This kills your Largest Contentful Paint score, a core metric for both SEO and UX.
- Skeleton screens with no actual preload. A fancy shimmer that hides the fact the real content is still miles away from rendering.
Each mistake subtly chips away at trust. Your page looks incomplete. Your UX feels laggy. Your rankings quietly sink. And your checkout conversion? It tanks.
Why this matters more than ever
In a world where e-commerce competition is ruthless and attention spans are shorter than a TikTok loop, the performance bar is sky-high.
Google has doubled down on performance as a ranking factor. And customers? They abandon slow-loading pages in seconds. The difference between a 1.5s and 2.5s load time isn’t just technical – it’s financial.
Lazy-loading is supposed to help. But when implemented sloppily, it actually:
- Decreases visibility. Search bots can’t index content that isn’t loaded.
- Harms trust. Blank states and delayed images feel unprofessional.
- Kills momentum. Shoppers lose the desire to browse when it’s clunky.
It’s like trying to run a race with your shoelaces tied together. You’re trying to go faster, but you’ve made the journey harder.
How to lazy-load correctly
The good news? It’s fixable.
Here are the core principles I use when advising e-com brands:
- Never lazy-load above-the-fold content. Your LCP element (usually a hero image or main product shot) should be eagerly loaded and preloaded via
link rel= "preload". - Audit JavaScript dependencies. Avoid relying on heavy JS libraries for basic image loading. Keep it lean.
- Use
IntersectionObserver, not scroll events. It’s native, performant, and better for battery and thread management. - Server-side rendering still matters. Don’t hide essential content behind JS that may or may not execute in time.
- Continuously monitor Core Web Vitals. Tools like PageSpeed Insights or Lighthouse can flag regressions before they cost you.
Remember, good lazy-loading should feel invisible. The page should feel instantaneous and seamless. If the user notices it, you’ve already failed.
The bottom line
Performance isn’t just a dev issue – it’s a growth lever.
And lazy-loading, when misused, can really be a silent killer. It drains SEO, dents trust, and crushes conversions, all while pretending to be a performance optimization.
So don’t just check the lazy-load box and move on. Treat it like the high-leverage opportunity it is.
Because in a world of infinite tabs and microseconds of patience, speed is trust. And trust is money.
See you next Saturday.