PageSpeed: LCP Request Discovery

Pages with a Largest Contentful Paint (LCP) request discovery that can be optimised.

LCP request discovery is the process of finding the specific file or resource that’s needed to display the main image on a web page.

Lighthouse checks to see whether the LCP image is discoverable from the HTML, has fetchpriority=high and is not lazy loaded.

How to Analyse in the SEO Spider

To populate this filter the PageSpeed Insights API must be connected via ‘Config > API Access > PSI’.

View URLs with this issue in the ‘PageSpeed’ tab and filter and use the lower ‘Lighthouse Details’ tab to click on the issue on the left-hand side, and see details of the LCP request discovery issues on the right-hand side.

Bulk export the pages and images via ‘Reports > PageSpeed > LCP Request Discovery’.

What Triggers This Issue

This issue will trigger if a page fails on any of the below checks:

1. Use fetchpriority=high on the image element, or on its preload directive.
2. Ensure the image is discoverable from the main document (either because it is directly in the HTML, or the image is preloaded).
3. Avoid loading=lazy for the image.

How To Fix

Optimise LCP by making the LCP image discoverable from the HTML immediately, using fetchpriority=high and avoiding lazy-loading.