Optimizing The Image Element LCP — Smashing Magazine

Largest Contentful Paint (or LCP) is one of three metrics of the Core Web Vitals. These metrics are used by Google to evaluate the quality of user experience. LCP measures the time it takes for the browser to load the main content in the viewport.

Since recently becoming a ranking factor, this major web performance KPI is still a new concept for many web developers. It becomes especially tricky to optimize when the LCP element is an image.

To address this problem, I’ll provide an overview of the best practices for the integration and optimization of an LCP image. I’ll cover the following:

• How to improve the LCP Resource load time subpart with the help of the <img> tag and a focus on proper LCP image sizing.
• Some explanations on the browsers’ behavior for this <img> tag and its attributes, so you can really understand and integrate your LCP image correctly.
• How to improve LCP Resource load delay subpart.

All the explanations will be illustrated by an example that we will iterate on. The images used in the article’s Codepen demonstrations will be integrated with TwicPics to save time in their creation and speed up the optimization of the LCP metric.

Note: The other LCP...