The Core Web Vitals are important performance metrics from Google’s point of view. In May 2021, these are going to have an impact on search engine rankings. Search Console already provides a simple view to these metrics.

PageSpeed Insights tool which relies on the LightHouse software from Google, indicates for traffic generating sites whether you have passed the Web Vitals test or not. According to this page, First Input Delay (FID), Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS) constitute the core web vitals.

This speed check tool also provides the assessment of these Google’s metrics. It will let you know whether you have passed the audit on performance benchmarks or not.

Also Read – Does Cloudflare Automatic Platform Optimization Improve Site Speed ?

What is Cloudflare APO

Automatic Platform Optimization (APO) from Cloudflare is a recent service that blogs about efficient TTFB and FCP times. Google fonts and JS resources. Caching of these things is also possible. If you are using the free plan of Cloudflare, then you can purchase this for $5/month for each site.

The Pro, Business and Enterprise plans have this APO service free. Included in the plans. It is an added benefit for the existing users.

Web Masters and developers using Cloudflare workers should be well versed with the advantage of APO. This feature is a worker KV (key-value) that uses JavaScript code and sits between the origin server and the end-visitor .

Also Read – Website Speed Test with and without PageSpeed Ninja and Cloudflare APO

Many CDNs only cache CSS, JSS, Images and attachment kind of resources. The number of locations limited to 10 to 13. This is quite contrary to the edge server locations supported by the Cloudflare APO service.

Cloudflare APO – Technical Details

Static content has the double benefit of speed and performance. But WordPress with PHP and database code limits this functionality. It may be useful to dynamic sites where there are shopping cart pages and on the go visitor pages.

Also Read – Core Web Vitals Test WITH and WITHOUT Optimization Plugin using GTMetrix

But APO serves HTML content from your nearest location including other resources. Since the free Cloudflare plan already supports the different data centers around the globe, this is like a top-layer to the free service.

Related Post :   Can Cloudflare Automatic Platform Optimization (APO) Improve TTFB and FCP

Sydney visitor will see some lag when the server location is in London. The time to first page content delivery is high.

APO caches HTML content close to your location. This reduce the initial response time. TTFB metrics also improve.

Influence on Core Web Vitals – PageSpeed Insights

I would like to know how much does APO has effect on the Core Web Vitals assessment of Google’s PageSpeed Insights tool. GTMetrix test done for the same page. Core Web Vitals were green in color. This is an indication that Cloudflare APO has a great benefit on Web Vitals.

GTMetrix has the best opportunity of deciding the test server, browser and device type. PageSpeed Insights test restricted to mobile and desktop. This is more reliable being a Google tool.

But an in-depth analysis is not possible using this tool. Waterfall analysis provided by GTMetrix is not provided by PageSpeed Insights. It only gives suggestions and recommendations on improvement.

Video ads, third-party code, java scripts, static assets without any cache policy are as errors. But GTMetrix does not implicate them as issues and shows them as good core web vitals.

Two different sites tested.

Core Web Vitals –  Mobile

The first site (#1) was using the DreamPress plan of DreamHost (managed wordpress hosting). It was also having Varnish cache and Fast Velocity Minify plugin.

This improves the page caching at the server level. It did not use AMP pages. So the benefit of that technology could not be measured here. This site had video and display ads.

The second site (#2) was on the shared hosting plan of DreamHost. This did not have the benefit of server cache. But cache optimization plugin (PageSpeed Ninja) was installed on this site. This site did not have any Ads. It was also using AMP technology for mobile responsive pages.

Site 1 –

The Lab Data shows the following details for mobile pages.

  • First Contentful Paint (FCP) – 4.2s
  • Speed Index – 9.5s
  • Largest Contentful Paint (LCP) – 5.0s
  • Time to Interactive – 13.5s
  • Total Blocking Time – 1440ms
  • Cumulative Layout Shift (CLS) – 0.172

The Origin Summary shows the following details.

  • First Contentful Paint – 2.4s
  • First Input Delay – 27ms
  • Largest Contentful Paint – 3.3s
  • Cumulative Layout Shift – 0.83

Since the mobile version was also serving video and display ads, the metrics were higher. But since we are not able to measure the TTFB values, this test does not conclusively say the benefit of initial page load speed of the site.

Related Post :   Does Cloudflare Automatic Platform Optimization Improve Site Speed ?

core web vitals mobile cloudflare apo pagespeed insights test

But if we observe the FCP values, they were also quite high on Google’s PageSpeed Insights test. The total score was also less. It was only 22. From this test perspective, it can be said that Core Web Vitals did not improve even after using the Cloudflare APO using this speed test tool.

Site 2 –

The origin summary was not detected for this site.

Lab data is the following.

  • FCP – 1.8s
  • Speed Index – 3.8s
  • LCP – 1.8s
  • Time to Interactive – 3.5s
  • Total Blocking Time – 40ms
  • Cumulative Layout Shift – 0.298

The mobile score was high as 93. The Core Web Vitals of LCP and CLS were also good.

core web vitals with cloudflare apo mobile

This shows that if you don’t have video and display ads, the performance metrics will be better. This site also had the additional advantage of using the AMP pages. This could also have been a factor in fast rendering of the site.

Core Web Vitals – Desktop

Site 1 –

The desktop score was higher compared to mobile. It was 70.

The Origin summary details were showing the following core web vitals.

  • FCP – 1.8s
  • FID – 3ms
  • LCP – 3.1s
  • CLS –  0.48

The Lab Data was showing the following details.

  • FCP – 1.3s
  • Speed Index – 2.5s
  • LCP – 1.6s
  • Time to Interactive – 2.7s
  • Total Blocking Time – 260ms
  • CLS – 0.155

In this test also, it can be seen that this speed test tool did not show remarkable improvement in Core Web Vitals.

cloudflare apo core web vitals desktop

Site 2 –

The desktop score was as good as 98. It was almost a perfect score.

The Lab Data was showing the following.

  • FCP – 0.5s
  • Speed Index – 0.9s
  • LCP – 0.5s
  • Time to Interactive – 0.5s
  • Total Blocking Time – 0ms
  • CLS – 0.219

As seen from the above data, the core web vital metrics were good for the desktop version also. PageSpeed Insights tool was giving good performance scores to this site. FCP values were lower and also the other metrics.

pagespeed insights test with cloudflare apo

This is a clear indication that Cloudflare APO has a benefit for this site. Though it could not be completely assessed of the TTFB times, it was showing remarkable improvement to the previous site.

Related Post :   Using Cloudflare to Improve WebSite Speed  to less than 90 secs

Since, page caching plugin was also being used, that could also have been a factor for good core web vitals.


The PageSpeed Insights test results were somewhat contrary to the GTMetrix test results. Though the same page (site #1) was used for testing the speed and performance metrics of the page, both were showing different results.

If we compare both the site pages, there are a lot of differences.

The main reason for site #1 showing high core web vital values could be because of Video ads and Adsense ads. These created JavaScript. Since they were being served from another server and could not be cached, it had a major influence of the Core Web Vitals.

Though Varnish cache and FVM plugin were being used on this site, it did not have effect on the core web vitals assessment. So, we can say that Adsense ads and Video ads will influence these metrics, even though APO was enabled for this site.

The second site (#2) was a plain site without any video ads or Google Adsense ads. Since only content, images were being served from this site, it had good Core Web Vital scores.

Also, it was using the page optimization plugin in the form of PageSpeed Ninja. AMP pages also had their benefit. So it cannot be said whether core web vitals were good because of APO or of cache plugin or of not having ads.

Waterfall Analysis of the effect of Cloudflare APO

Also, GTMetrix was using the Lighthouse tool. It also gave in-depth analysis of the loading time of the resources. We could clearly see when the first page was being served. It was showing major improvement in this area.

Without using Cloudflare APO, these values were much higher. Since APO was expected to reduce the TTFB and FCP, the same could not be measured using this tool. But the other Core Web Vitals from this test were not green and showed degraded performance.

Unless we test the same web page from different test server locations, we cannot confirm the influence of Cloudflare APO on Core Web Vitals.

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