web performance and seo
Lazy loading
A web performance technique that defers loading off-screen images until users scroll near them.
What is Lazy loading?
Lazy loading is a web performance technique that defers downloading off-screen images until users scroll close enough for them to enter the visible viewport. This reduces initial page weight by loading only images visitors will actually see, rather than downloading every image when the page first loads. Native lazy loading became available in 2019 with the `loading="lazy"` HTML attribute and is now supported by 95% of browsers globally.
Importance of Lazy loading
Without lazy loading images, websites download every image immediately even if users never scroll to see them — wasting bandwidth and slowing initial page loads. Google's research shows below-the-fold images account for 30-50% of page weight on typical websites, representing significant unnecessary data transfer. For Pictuary users optimizing images for web use, lazy loading ensures your compressed images deliver maximum performance benefits by loading only when needed.
Lazy loading in Practice
A typical blog post with 20 images might have only 3-4 images above the fold that users see immediately. Without lazy loading, the browser downloads all 20 images on page load — potentially 2-3 MB of data. With `loading="lazy"` applied to below-the-fold images, initial page weight drops to just the above-the-fold images, reducing bandwidth by 70-80% and improving load times by 2-3 seconds on mobile connections.
Lazy loading Best Practices
- → Add loading="lazy" to all images except your above-the-fold hero image
- → Never use lazy loading on images visible in the initial viewport to avoid LCP delays
- → Test your implementation to ensure lazy-loaded images appear smoothly as users scroll
- → Combine with optimized image formats like WebP for maximum performance gains
Example of Lazy loading
Related Terms
Frequently Asked Questions
What is lazy loading and how does it work?
Lazy loading defers downloading images until they're about to become visible as users scroll down a page. The browser monitors scroll position and starts fetching lazy-loaded images approximately 1,250-2,500 pixels before they enter the viewport, ensuring they're ready when users reach them. This reduces initial page weight by loading only visible content first.
Should I use loading lazy on all images?
No, never use `loading="lazy"` on above-the-fold images that are visible when the page first loads. Lazy loading these images delays their download unnecessarily, harming LCP performance and Core Web Vitals scores. Only apply lazy loading to images below the initial viewport that users must scroll to see.
Does lazy loading work on all browsers in 2026?
Native lazy loading with `loading="lazy"` is supported by approximately 95% of browsers globally, including Chrome 77+, Firefox 75+, Safari 15.4+, and Edge 79+. The remaining 5% of browsers simply ignore the attribute and load images normally, providing graceful degradation with no negative effects. JavaScript libraries are no longer necessary for standard image lazy loading.