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Can A CDN Cause Google Page Experience Problems? [2024] 💥

Can A CDN Cause Google Page Experience Problems?

In today's digital landscape, ensuring an optimal user experience is crucial. The performance of a website often hinges on a myriad of factors, one of which is the Content Delivery Network (CDN). While CDNs aim to enhance the speed and reliability of web content delivery, they might inadvertently cause Google Page Experience issues. But how exactly can a CDN impact your website's standing in Google's eyes? Let's delve deeper.


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Understanding Lab Data and Real-World Data

Lighthouse primarily offers "lab data" for debugging, helping developers pinpoint areas for improvement on a page. However, it's essential to realize that these numbers are only a rough estimate and can differ from real-world experiences.

On the contrary, Google Search Console relies exclusively on real-world data for its scores in page experience and issue detection. This data is collated using the CrUX tool, capturing analytics directly from users' browsers, provided they have the usage statistics option enabled.

It's vital to understand that the mechanism used by CrUX for gathering real-world data is distinct from that used for lab data; it doesn't operate on the Lighthouse engine.

Decoding the Priority of Data

The way Google processes and prioritizes data for Page Experience follows a structured hierarchy:

  1. If a URL attracts significant real-world traffic from users with the statistics option enabled, CrUX generates a Field Data Report.
  2. If insufficient real-world data exists for a particular URL, the system defaults to the origin summary report.

The Field Data Report is formed by averaging out metrics for every real-world view (like FCP, LCP, CLS, FID) and determining the percentage of views that qualify as green, yellow, or red for each metric. A URL is deemed "good" if the total score exceeds 90% for at least 75% of the real-world views. Nevertheless, such a URL should also be devoid of mobility, security, and ad experience issues to retain its "good" status.

When Field Data Reports Are Absent

Not having a Field Data Report doesn't imply a complete absence of field data. Instead, it usually indicates that there's not enough data to derive a concrete aggregated score or conclusion for that URL. In such cases, Google may inherit scores from a "similar" URL with sufficient field data or fall back on the origin summary.

Interpreting the Origin Summary

The origin summary is potentially an average of views from all pages, aggregated together. It can be influenced by just a handful of pages performing poorly, thereby impacting the overall score for a domain.

The Solution to Page Experience Woes

Understanding why certain URLs are performing poorly is half the battle. For instance, if a website's initial traffic was directed towards pages with subpar performance, it could skew the origin summary. Improving these pages is a step forward, but without adequate traffic, these efforts won't reflect in the Page Experience scores.

To rectify this, one might consider the following:

  • Enhance the overall user experience across all pages.
  • Generate more traffic post-improvements to influence the origin summary positively.
  • Focus on specific URLs, driving traffic to them individually to obtain a field data report.

If certain URLs are erroneously labeled as "bad" despite improvements, it's imperative to direct traffic to them. Without real-world views, their status remains unchanged, no matter the number of validation reports run.

Why Lighthouse Lab Data Can Vary

Running Lighthouse multiple times for the same link can yield differing results due to reasons like:

  • Server response time variations based on traffic, load balance, and more.
  • Differences in how the Lighthouse engine processes the data.
  • External factors, such as third-party resources or CDNs.

Real-World Data Variations

Real-world data, not being reliant on Lighthouse, is influenced more significantly by the client's device characteristics, browser type, installed plugins, and even internet speed. With such a vast array of variables, it's understandable why real-world data might differ drastically from lab data.

CDNs and the Potential Risks

While CDNs, like Cloudflare, offer accelerated content delivery, they can inadvertently impact the CLS scores. If your CLS scores dip below 75%, Google might penalize your website, affecting its position in the Search Engine Results Page (SERP). It's particularly risky to use Cloudflare's Free CDN service, given its potential to cause CLS problems.


Ensuring an optimal user experience is a multi-faceted endeavor. While CDNs aim to boost website performance, it's vital to monitor their impact, especially on Google Page Experience scores. Falling below the acceptable CLS range can lead to Google penalties, making it paramount to be cautious when utilizing CDN services, particularly the free versions. As the digital landscape evolves, staying informed and adapting is key to maintaining and improving website performance and user experience.


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