Some new data from a recent Core Web Vitals (CWV) Technology Report produced by HTTP Archive shows that WordPress sites running newer versions have lower CWV success rates.
The original report was published in July by Rick Viscomi, one of the HTTP Archive maintainers. The website provides a permanent repository of web performance information, giving researchers a common set of data to research and understand trends. Contributor efforts are sponsored by Google, Mozilla, New Relic, Etsy, and other companies.
One of the most notable findings of Viscomi’s report showed that only 22% of WordPress-powered origins exceed the Core Web Vitals “good” threshold.
Adam Silverstein, WordPress core committer, wanted to dig a little deeper into this data set to see if he could extract more information about the CWV performance of WordPress sites that was not represented in the graphs originally published. He offered an analysis that compare Core Web Vital performance between WordPress versions:
How have CWV scores changed over WordPress releases? Are there any measurable improvements in nature after recent changes like adding native picture (version 5.5) and iframe (version 5.7) lazy loading and WebP image support (version 5.8)?
Silverstein worked with Viscomi to create a query that would pull performance data grouped by version of WordPress. It found that basic additions like native image and lazy iframe loading, and support for WebP images had no measurable improvement on CWV scores in the wild.
“Lazy loading can be too aggressive because it’s applied to all images,” Silverstein said, noting that lazy loading can be detrimental if overused. This should be fixed soon. Google Sponsored WordPress Lead Sponsor Felix Arntz Opened a ticket to improve lazy loading, which will be included in WordPress 5.9.
“Adoption of WebP in WordPress has increased since version 5.8, but users must manually convert their images to WebP before uploading to take advantage of the format,” Silverstein said. “Landing WebP as default format for reduced size images which was started in this post will have a much greater impact by automatically converting uploaded images to WebP.”
Here are some highlights of Silverstein’s observations from the scan:
- 70% of origins are on the latest version of WordPress and 88% are on one of the last two versions, which means that the changes we make to the core reach the majority of sites fairly quickly.
- The number of origins is quite low for older versions of WordPress, with less than 5,000 origins for most versions prior to 4.7
- Overall CWV success rates have generally decreased compared to WordPress releases. Although it can also happen that “peak” websites that update to the latest version are generally slower than those that dwell on older versions.
Silverstein expects this analysis to provide the basis for tracking major improvements in the future. the Google-sponsored WordPress contributors on his team are active in some core projects and lead the new WordPress performance team with the goal of improve baseline performance as measured by Google’s Main Web Vitals metric.
“Basically, I wanted to create a way to measure the impact of core WordPress improvements on (large-scale) WordPress sites,” Silverstein told The Tavern. “My team at Google is focused on improving web performance at scale, and WordPress is a huge part of that! You may have noticed that we’re working on features like lazy-loading images and iframes, WebP image support and which we are now helping to start the performance group I wanted to find a way to see if our work is having a measurable impact – and not just on a vanilla WordPress site that you might set up for testing, but in the wild or on real-world websites upgrading to the latest version of WordPress.That’s the goal of the dashboard.
New dashboard, which tracks WordPress CWV performance by release, is available to the performance team to track their progress with each new release of WordPress. Google-sponsored contributors use it to measure the impact of their efforts on various performance initiatives.