Learn · Performance & optimization
Lazy loading means loading content only when it's needed, usually as the user scrolls toward it, rather than all at once up front. Images and sections below the fold wait until they're about to be seen. This makes the initial page load faster and saves data.
The benefit is that a long page with many images doesn't force the visitor to download everything before they see anything. The top of the page appears quickly, and the rest loads just in time as they scroll.
It should be applied carefully: lazy-load offscreen images, but not the main above-the-fold image, which you want to load immediately for a fast LCP. Done right, lazy loading improves speed without the user ever noticing the mechanism.
Updated July 2026
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Compress images, use modern formats like WebP or AVIF, size them to how they'll actually be displayed, and load offscreen ones lazily. Images are usually the heaviest part of a page, so optimizing them is the single biggest speed win on most sites.
LCP measures how long it takes for the largest visible element (usually the main image or heading) to load and appear. It's the closest single number to "how fast does this page feel to load." The target is under 2.5 seconds for the good rating, measured on real visitors.
Core Web Vitals are Google's three metrics for real-world page experience: LCP (loading speed), INP (responsiveness), and CLS (visual stability). As of July 2026 the "good" targets are LCP under 2.5 seconds, INP under 200 milliseconds, and CLS under 0.1, measured on real visitors at the 75th percentile.
INP measures responsiveness: how quickly the page reacts visually after you tap, click, or type. It replaced the older FID metric in March 2024 and looks at interactions across the whole visit, not just the first. The target is under 200 milliseconds. It's the most commonly failed vital in 2026.
CLS measures visual stability: how much the page unexpectedly jumps around as it loads. The target is under 0.1. You've felt bad CLS when you go to tap a button and an image or ad loads above it, pushing everything down so you tap the wrong thing.
Speed affects money directly. Faster sites keep more visitors, convert more of them into customers, and rank better in search. Study after study shows that as load time rises, people leave and sales drop. A slow site quietly loses revenue before anyone reads a word of your content.