Frontend engineering · Performance

Lazy Loading

Also called: Deferred loading, Load on demand, Lazy load

Load assets or components only when needed—entering the viewport, opening a route, or expanding a panel—to lighten the first paint.

In detail

You can lazy-load images, below-the-fold widgets, or rare modals. Images use loading="lazy" or assign src on intersect; components use dynamic import.

Overuse makes critical above-the-fold content pop in late and can hurt SEO/LCP. Hero images and critical CSS should not be lazy.

Together with code splitting: split first, then fetch at the right time.

Developer infoTerm ID, DOM cues, match priority

Term ID: eng-lazy-loading
DOM selectors: No DOM cues. This concept isn't detected directly on a page.
Priority: 1 · when several match at the same level, the higher priority wins
Version: v1 · updated Oct 5, 2026