Smart LazyLoad

The best free, simple & lightweight lazyload plugin for WordPress websites. Lazy loading images, videos, and iframes to improve page speed performance and Core Web Vitals scores.

Most lazy load plugins only optimize images. Smart LazyLoad goes further by deferring images, responsive <picture> sources, background images, native HTML5 videos, and iframes (including YouTube, vimeo) until they are about to enter the viewport.

Built with the simple, lightweight Vanilla LazyLoad JavaScript library that uses modern browser APIs without requiring jQuery. Smart LazyLoad also includes native browser lazy loading support, smooth loading effects, and intelligent defaults, so it works well immediately after activation.

Unlike most lazy load plugins, Smart LazyLoad gives you two levels of control. A global Master Switch lets you enable or disable lazy loading across your entire website, while a per-post override allows individual posts and pages to follow the global setting or force lazy loading on or off when needed.

Everything is managed from a clean, modern settings page where you can choose what to lazy load, fine-tune performance, customize placeholders and animations, and exclude specific elements for maximum compatibility.

Features

What gets lazy loaded

• Images — inside post/page content, featured images, widget images, and avatars.
• Responsive <picture> sources — defers every <source> inside a <picture> element (WebP, hi-DPI, art-directed crops) in lock-step with its fallback <img>, so the browser’s format/media negotiation is never affected, only when it happens.
• Background images — inline style="background-image", a manual data-bg attribute, and retina/responsive backgrounds via CSS image-set() or a manual data-bg-set attribute, picking the best resolution for the visitor’s screen.
• Iframes — any embedded iframe, including YouTube and Vimeo players.
• Native <video> — HTML5 <video> tags, their <source> children, and poster images.
• YouTube click-to-play thumbnails — an optional mode that replaces a YouTube iframe with a lightweight clickable thumbnail until the visitor actually wants to watch it.
• Smiley images — text smilies (e.g. :mrgreen:) that still resolve to an image file are lazy-loaded like any other image; smilies rendered as Unicode emoji are unaffected.

Two layers of on/off control

• A single Master Switch turns the entire plugin on or off for the whole site
• Turning the Master Switch off automatically dims and locks every other setting on the page so it can’t be edited by mistake — but nothing is ever cleared; your configuration reappears exactly as you left it the moment you switch it back on
• A Smart LazyLoad panel on the post/page editor sidebar adds a single Lazy Load dropdown — Default, Enable, or Disable — so any individual post or page can override the site-wide behavior without touching a single other post

Performance tuning

• Automatically skips lazy loading the first image on the page, protecting your Largest Contentful Paint (LCP) score
• Adjustable distance-from-viewport threshold that controls how early loading starts
• Choice between the plugin’s own IntersectionObserver-based engine or the browser’s native loading="lazy"
• Loads its own script in the footer instead of the head, so it never delays first paint
• Can be switched off entirely for logged-in users, so you always see full-quality content while editing

Appearance while content loads

• Low-quality image placeholder (LQIP): a tiny, blurred preview generated from an existing thumbnail size, shown instead of a blank box
• The preview is generated once per image and cached as post meta, so it costs nothing on later page loads
• A WP-CLI command (wp smart-lazyload generate-lqip) pre-generates placeholders for your whole media library at once, so large sites never pay the one-time generation cost on a live visitor’s request
• Pick which registered image size is used to generate the preview
• Configurable fade-in duration for the moment content finishes loading
• Optional placeholder background color, picked with the native WordPress color picker

Compatibility and control

• A multi-line custom exclude field — list your own classes or attributes to skip, no code required
• Built-in recognition of common exclusion conventions: no-lazyload, skip-lazy, data-no-lazy, data-skip-lazy
• Automatically stays out of the way inside page builder editors (Elementor, Avada, Divi, Beaver Builder, WPBakery, Oxygen) and on feeds, previews, and REST requests
• Developer filters for replacing placeholders and disabling lazy loading conditionally
• One-click “Reset to Defaults” whenever you want to start over

Read the full description on the official page →