: For the Largest Contentful Paint (LCP) image—usually the main hero image—using decoding="async" can actually delay its appearance, potentially hurting your Core Web Vitals scores.
: Moving the decoding process to a background thread keeps the main thread free, ensuring a smoother user experience and reducing "jank" while scrolling. <img decoding="async" class="alignleft" src="ht...
249: Decoding async, tree rings, and flexbox gap - CSS-Tricks : For the Largest Contentful Paint (LCP) image—usually
While async decoding is generally a best practice for secondary images, it can occasionally backfire for critical "above-the-fold" content: The attribute decoding="async" in an tag is a
: Because the browser might paint the rest of the page before the image is ready, the image may "pop in" suddenly after the surrounding text is already visible.
The attribute decoding="async" in an tag is a performance-focused hint that tells the browser to decode image data off the main thread. This prevents the CPU-intensive process of converting a compressed file (like a JPEG) into raw pixels from blocking the rendering of other critical content, such as text or interactive elements. Why decoding="async" Matters
When a browser downloads an image, it must decode it before it can be displayed. By default, many browsers perform this synchronously, meaning they wait for the image to decode before showing the rest of the page content.