Core Web Vitals Update: Assessing the Initial Impact

The internet is a bleeding edge technology and the core web vitals report offers an early look at how well companies are managing their digital presence. This week we take a long-term view on eight key metrics to see where they stand now in the face of emerging technologies like cryptocurrency, augmented reality, and machine learning.

The “Core Web Vitals Update” is a report that assesses the initial impact of the changes in the Google algorithm. It does not pass the core web vitals assessment.

We already discussed how to be ready for the 2021 Core Web Vitals upgrade a few months ago. 

The new version is already available. It was first launched in June of 2021. Its deployment, unlike the others, is planned to take a few months, so it’s too early to gauge the whole impact. 

However, as we near the completion of the first half of the upgrade, which is set to be live in August, we thought it would be interesting to look at some early patterns.

A Brief Background on the Page Experience Update

The Core Web Vitals (CWV) are a component of Google’s Page Experience Update, which emphasizes user-friendliness signals in determining page ranks.

CWV is simply a collection of measures that include:

  • The render time of the biggest image or text block displayed inside the viewport in comparison to when the page initially began loading is measured by Largest Contentful Paint (LCP).
  • The visual stability of a page is measured by Cumulative Layout Shift (CLS).
  • Interactivity is measured by the First Input Delay (FID) (how quickly users can interact with the elements on a page).

Check out this article for a more in-depth look at Core Web Vitals. 

It’s Not Always Difficult to Find Core Web Vitals

with the help of Webinomy Site Audit

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Update on the Core Web Vitals: Measuring the Interim Impact

The summer of 2021 was jam-packed with new information. It’s crucial to note that, in addition to the expanded Page Experience upgrade, we had two major core algorithm improvements in June and July, as well as an Anti-Spam update.

Although factors other than the Page Experience Update might have affected SERPs, we wanted to examine the early effect of Core Web Vitals, thus we employed the following methodology:

  • We gathered the top 10 results from SERPs on both the desktop and mobile web using over 2,500 random terms from Webinomy Sensor’s US database.
  • We gathered SERPs for the following dates: June 8, 2021 (before to the implementation), June 21, 2021 (immediately after the rollout), and July 15, 2021. (roughly one month into the rollout). 
  • We compared the numbers for the three days while measuring the Core Web Vitals metrics* for all the URLs that made it into the top 10 search results.

We studied over 18,000 URLs in June before and after the upgrade, as well as in July, to see whether there were any possible mobile SERP alterations. We examined over 19,000 URLs for the same durations to evaluate the condition of desktop SERPs. 

The discrepancies we were able to detect owing to the examination of all the collected data are detailed in this post. We employed both lab and outdoor data in this investigation, with the latter having a ranking effect.

Before we go into the details of the results, it’s important to note the fundamental differences between field and lab data:

  • Field data is based on statistics from actual users, who each access the website using a different device and network connection. 
  • Data is gathered in a controlled environment with pre-defined device and network connection parameters. Data from the lab is used to simulate a Moto G4 phone with a high-speed 3G connection.

As a result, CWV ratings from field and lab data are likely to vary.

*Please note that for lab data analysis, we used Total Blocking Time (TBT) instead of First Input Delay (FID). FID cannot be measured in the lab since it needs data from actual users. According to Google, the lab-measurable TBT measure corresponds with FID in the field, indicating concerns with interaction.

What Has Changed Since the Update Began?

The Key Findings Are Being Revealed

  • The post-update statistics for June and July showed no significant differences. The general situation hasn’t changed significantly, according to field data**. However, we noticed a few minor details in the lab statistics.
  • The total percentage of URLs with all metrics categorized as ‘Good’ grew for both mobile and desktop, according to lab data. 

**Because field data might take up to 28 days to refresh its statistics, check back for the next edition of our research to see whether field data yields different results.

The following is a list of all the statistics for both lab and field data:


Disclosing More Extensive Findings

Data from Mobile SERPs

For each CWV measure, there is a distribution of URLs. 

All three indicators we assessed before, during, and one month after the upgrade showed relatively minimal changes, according to field data.

For FID and CLS measurements, the majority of URLs have ‘Good’ values. We see just as many pages in the ‘To improve’ area as we do in the ‘Good’ range with LCP.

However, laboratory data enables us to take a more detailed look:

  • Since the start of the upgrade, the number of sites in the ‘Good’ LCP range has grown, while those in the ‘Poor’ LCP range have faded from mobile SERPs. However, since the noticed modifications were by a minor 3 percent margin, not a statistically significant amount, we can’t draw any inferences.
  • Even after an update, the bulk of URLs have ‘Poor’ TBT. However, we can observe that the number of ‘Poor’ pages declined by 10% immediately after the upgrade, before returning to pre-update levels in July. For URLs with ‘Good’ TBT values, we notice a similar ‘bounce back’ tendency. So yet, this is only an observation since no apparent reason has been identified (if any).
  • Prior to the upgrade, the majority of URLs had a ‘Good’ CLS score, with a consistent rising trend in all three data sets.

Trying to figure out whether there’s a link between Core Web Vitals and mobile rankings

While we did look at the top-ranking URLs to see how they rank in terms of CWV, this does not mean that their high rankings are due to high CWV values.

As a result, our examination of the condition of SERPs from a CWV viewpoint follows the old adage that “correlation does not imply causation.” 

We looked at URLs that scored ‘Good’ on all three measures and determined where they often appear in SERPs. 


According to the statistics, the link between ‘Good’ values and positions was extremely simple prior to the upgrade – the lower the percentage of sites with all ‘Good’ metrics, the lower the SERP. 

Since the upgrade, Google has taken a cautious approach, leveling out the remainder of the SERPs rather than adjusting the top positions due to CWV variables.

However, this information does not suggest that CWV-related variables influence SERPs. 

Data from SERPs on Desktop

Because the Page Experience Update currently primarily affects mobile search results, we concentrated our efforts on mobile SERPs. 

However, since Google announced that the upgrade would be rolled out to desktop as well, we looked at how desktop SERPs fared in terms of CWV-friendliness.

For each CWV measure, there is a distribution of URLs. 

The following statistics show the percentage of URLs that fall inside the ‘Good’ category for all three CWV metrics:

  • According to lab statistics, following the upgrade, desktop SERPs have returned 10% more all-good URLs.
  • According to field statistics, there has been a 3% drop. 

In comparison to mobile, desktop statistics indicate a more clear improvement trend for all CWV metrics:

  • The bulk of sites in the top ten places on desktop SERPs have an LCP of ‘Good.’ 
  • On both mobile and desktop SERPs, we observe a comparable percentage of sites in the ‘To improve’ TBT range. The bulk of PC URLs have ‘Good’ TBT values, unlike mobile data. This is to be anticipated, since passing the requirements on a PC is simpler than on a mobile device, which simulates a 3G network. However, one month after the update, the metric’s values had degraded by just 1.5 percent compared to pre-update levels. 
  • The vast majority of URLs fall under the ‘Good’ CLS category.

What’s Next for the Core Web Vitals in 2021?

As you can see, preliminary data suggests that analyzing the effect of Google’s Page Experience upgrade is premature. 

We haven’t seen any substantial changes in rankings yet, and we haven’t been able to correlate them to CSW characteristics, so it’s difficult to identify any regular trends at this time. However, preliminary study suggests that there is a general improving tendency in CWV.

However, we still have another month to witness the entire rollout, and we will certainly reevaluate our impact estimate once the upgrade is complete in August. So keep tuned for a thorough examination of the Page Experience Update’s aftermath in our data studies.

In the meantime, while the update is still rolling out, make sure to use data from tools like Site Audit (don’t forget to use site improvement ideas from the Performance Report), as well as field data from Google Search Console and PageSpeed Insights, to prepare your website for the Page Experience Update’s final stage.

It’s Not Always Difficult to Find Core Web Vitals

with the help of Webinomy Site Audit

ADS illustration

The “core web vitals case study” is a research conducted by the company Core Web Vitals. The study was conducted to assess the initial impact of core web vitals on websites that were using it.

Frequently Asked Questions

What is the Core Web Vitals update?

A: Core Web Vitals is a reworking of the way the web server works in Beat Saber. It was released on June 11th, 2019 and allows for faster load times for players who have lower bandwidth connections or those that are just connecting from outside their country.

Does Core Web Vitals affect ranking?

A: No, Core Web Vitals does not affect your ranking.

What is Core Web Vitals why it is important?

A: Core Web Vitals is a weekly publication of the most extreme and heavily trafficked websites on the internet. It provides data such as Alexa rank, traffic rankings, uptime percentage and many other metrics to help you decide which website(s) would be best for your customer base.

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