Lazy load images
Toggle: LazyLoad images. When on, the browser only loads images that are visible in the viewport. Images further down the page wait until the user scrolls toward them. Major win on long pages with many images (galleries, blog archives, product listings).| Sub-toggle | What it does |
|---|---|
| LazyLoad iframes and videos | Same idea for <iframe> and <video> tags. YouTube and Vimeo embeds get their thumbnail right away but only load the player iframe on scroll. |
| Replace YouTube videos with preview images | Stronger version: even the iframe waits until click. The thumbnail is shown statically. Largest perf win for sites with many video embeds. |
What lazy load doesn’t catch
LazyLoad hooks into<img> and <iframe> tags in the HTML. It misses:
- Images set via CSS (
background-image: url(...)). - Images injected by JavaScript after page load.
- Images inside
<style>tags with embedded data URIs. - Page builder content (Elementor and friends) that renders via shortcodes.
Font optimization
Toggle: Reduce font-related layout shifts. Web fonts are a common source of CLS (Cumulative Layout Shift, a Core Web Vitals metric). When the page renders with the fallback font, then re-renders when the web font loads, every text element shifts. Browsers grade you on this. When enabled, AccelerateWP injects@font-face rules with CSS metric overrides that match the web font’s metrics to the fallback. The fallback renders with the web font’s spacing, so when the swap happens, nothing visibly moves.
Default: on. There’s no real downside to leaving it on.
Supports:
- Google Fonts URL imports.
@font-facedeclarations in your stylesheets.font-familydeclarations that resolve to web fonts.
Image dimensions
Toggle: Add Missing Image Dimensions. When an<img> tag is missing the width and height attributes, the browser doesn’t know how much space to reserve until the image loads. The page reflows when it does, causing layout shift.
When on, AccelerateWP scans HTML output, fetches image metadata server-side, and injects width and height attributes into <img> tags that are missing them.
What it doesn’t touch:
- Images that already have
widthandheightset (no need). <picture>tags.- SVGs (intrinsic dimensions come from the SVG).
- External images (anything not on your domain; AccelerateWP can’t fetch the metadata reliably).
Common issues
Images don't load at all on some pages
Images don't load at all on some pages
Likely lazy load is hiding them behind a JavaScript trigger that isn’t firing. Check the browser console for JS errors. If a deferred or delayed script is breaking, File optimization → Excluded JavaScript Files can let it run normally.
A specific image needs to load immediately (above the fold, hero)
A specific image needs to load immediately (above the fold, hero)
Lazy load every image including the hero hurts LCP, the Largest Contentful Paint metric. Add a
class="no-lazy" attribute to the <img> tag in the theme. AccelerateWP recognizes that class as an opt-out.Page builder images (Elementor, Divi) aren't being lazy-loaded
Page builder images (Elementor, Divi) aren't being lazy-loaded
Elementor and Divi render images via background-image CSS or via JS hydration. AccelerateWP’s lazy load only catches
<img> tags in the HTML. Use the page builder’s own lazy-load setting alongside AccelerateWP’s.Font optimization made my fonts look subtly off
Font optimization made my fonts look subtly off
The fallback font’s metrics don’t match closely enough to the web font for a clean handoff. Disable Reduce font-related layout shifts and accept the small CLS hit, or pick a fallback font with closer metrics in your CSS.
Image dimensions are sometimes wrong (stretched)
Image dimensions are sometimes wrong (stretched)
AccelerateWP fetched stale dimensions for an image that was later resized in WordPress. Re-upload the image, or clear the AccelerateWP cache after re-saving the image in WordPress.

