php – Featured Images and Google LCP
I’m seeing a very interesting development with the_post_thumbnail() now that Google has added the page experience to the Google search console, now you can see page experience and I have 51 pages fail LCP because of
<?php if (has_post_thumbnail( $post->ID ) ): ?> <?php $image_alt = get_post_meta( '_wp_attachment_image_alt', TRUE);?> <div id="post-img-header"> <?php the_post_thumbnail( 'post-header'); ?> </div> <?php endif; ?>
Using the_post_thumbnail even though this image is optimized is seeing a 20 page-speed point decrease in both page-speed and lighthouse. If i swap this image out for a normal tag i do not see this issue.
I have added an image CDN and now deliver the_post_thumbnail as WebP but this still does not make the same difference that removing post thumb and adding in a normal image tag does.
it’s not even like these are huge images in dimensions or even file size (72.7 KB)
and it is only happening to pages that use the_post_thumbnail which is really just our blog all other pages are using ACF images that do not see an LCP fail issue.