Fetchpriority attribute default now on WordPress 6.3

Using the default settings will have a negative impact on the performance of the page.

Here is a brief explanation of what the WordPress version update is all about:

WordPress 6.3 introduces several updates aimed at enhancing the loading efficiency of image-rich content. These improvements are particularly noticeable in the Largest Contentful Paint (LCP) metric. LCP measures the time taken from the initial request to when the largest visible content item is fully displayed on the screen.

Overview of Updates:

The enhancements include:

• WordPress now intelligently assigns a “high” fetchpriority value to the image it identifies as the most significant for LCP—typically the largest image within the viewport. This attribute signals the browser to give download priority to this image, even before layout calculations are complete. Such prioritization has been shown to boost LCP performance by approximately 5-10%. More details can be found in the proposal that initially suggested this feature.
• There have been additional refinements and bug fixes to enhance the automatic management of the lazy-loading attribute for images. This builds on efforts that began with WordPress 5.9 and were further developed in version 6.2. A comprehensive review in WordPress 6.3 addressed the remaining challenges, optimizing how and when to bypass lazy-loading for certain images—especially those critical for LCP. This strategy is crucial for enhancing site speed, as outlined in the development notes from WordPress 5.9.
• The integration of fetchpriority support required some restructuring to separate the detection of images within the viewport from lazy-loading functionalities. Consequently, both fetchpriority and loading attributes are now managed by a unified function within the WordPress core. Developers who have integrated specific aspects of WordPress’s lazy-loading mechanism into their plugins or themes should note these changes for potential adjustments.

Luckily I found a fix for one of my clients whose LCP increased by 300ms due to this default version.

Steps to Fix:

The fix is to go to wp-includes/media.php from server files or FTP

Then search for “wp_min_priority_img_pixels” inside the code and update the 50000 to 5000000

After that search for “Images should have dimension attributes for the ‘loading’ and” and update with the number as shown in the screenshot below:

Save and test your results; make sure to get before and after the performance review. If you like this method, please share this post in your blog and add a citation to this blog with the link https://washeen.com/fetchpriority-attribute-default-now-on-wordpress/