What is Core Web Vitals Assessment Failed on Pagespeed

Pagespeed marks your site with “Core web vitals assessment failed” when you fail to hit the “Good” threshold for any current metrics, LCP, CLS, or FID(INP in the future). 

The metrics data come from Chrome browser users and are based on a 28-day collection period window.

There’s confusion around this information, as many websites have a good Lighthouse speed performance but still get the assessment failed label. The simple answer to this is that one is field data, which is data from real users. Pagespeed runs on test devices, known as lab data.

Google may be working on clearer guidance on this matter, to diminish confusion.

To get passing metrics you need to solve the underlying issues marked in the report. Only fixing Lighthouse issues and attempting a 100 score won’t make the Core Web Vitals pass, you should focus on the field data to solve it.  

What happens if you fail Core Web Vitals?

There’s no mention of penalizing failing metrics on Google websites. Google says regarding the Page Experience(Core Web Vitals plus 4 other signals) algorithm:

“Good status will be used as a ranking signal for a URL in Google Search results on desktop or mobile devices.”

and:

“Google Search always seeks to show the most relevant content, even if the page experience is sub-par. But for many queries, there is lots of helpful content available. Having a great page experience can contribute to success in Search, in such cases.”

How to pass the Core Web Vitals Assessment

For Pagespeed to recognize your ULR-level or Origin metrics as passing, you need to fix the underlying issue, either LCP, CLS, or FID. 

How to Improve Wordpress LCP

1. Set the Fetch Priority High of the LCP
2. Delay, Defer, or inline render-blocking JavaScript
3. Setup Critical CSS
4. Remove unused CSS
5. Host Google Fonts locally
6. Avoid Combine CSS or JS
7. Switch to leaner HTML elements
8. Use CDN for images and SVGs
9. Use Cloudflare APO
10. Improve icon font loading or switch icons to SVG
11. Limit access from users with bad Core Web Vitals

How to Improve Wordpress CLS

1. Edit the element layout
2. Unload Large Unused CSS in between the loading of elements
3. Use Critical CSS or Remove Unused CSS
4. Avoid Sliders plugins
5. Apply correct image and div sizing
6. Move CSS from theme editor to child theme style.css
7. Prefer themes and plugins that use transform animations

How to Improve Wordpress INP

1. Choose plugin or theme features wisely
2. Run third-party scripts off the main thread in Web workers
3. Choose Iframes wisely