PageSpeed Insights and Raptive Ads

If you use PageSpeed Insights (PSI) to test your site’s performance, it’s important to understand the difference between field data and lab data — and how each relates to your site’s real-world performance and Raptive ads.

When you generate a PSI test, the report includes two main sections:

1. Field data (Core Web Vitals Assessment)
2. Lab data (Diagnostics & Performance Score)

Each serves a different purpose and should be interpreted accordingly.

Read more -> Google's documentation on PageSpeed Insights

What is field data

Field data shows how your site performs for real people. It measures performance metrics for every user who visits a page. It can also be referred to as Real User Monitoring (RUM) data. Both terms can be used interchangeably. 

What it measures

Field data metrics are collected from Chrome User Experience Report (CrUX) data and reflect how your site performs across different devices, networks, and locations.

The metrics are Google's Core Web Vitals:

• Largest Contentful Paint (LCP) – measures how long it takes for the main content to load.
• Interaction to Next Paint (INP) – measures responsiveness by tracking how quickly the page reacts to user interactions.
• Cumulative Layout Shift (CLS) – measures visual stability and unexpected layout movement.

Why it matters

Field data is what Google uses for SEO rankings. It accounts for factors like asynchronous loading, ad code execution, and real-world user interactions — making it the most accurate reflection of how people experience your site.

Relation to Raptive ads

Raptive ads and scripts are designed to load asynchronously, meaning they load after your primary content, without blocking rendering or delaying user interactions. Because of this, ad-related scripts generally do not negatively impact Field Data metrics such as LCP, INP, or CLS.

We recommend focusing your optimization efforts on passing all Core Web Vitals metrics in the Field Data section, as that’s what affects both user experience and search ranking.

What is lab data

Lab data measures how a page performs in a controlled setting. It utilizes a predefined set of network and device conditions, known as a lab or synthetic environment, to simulate the user experience.

What it measures

Lab data comes from a controlled, simulated test performed on a single device type and connection speed. It measures metrics including:

•  Total Blocking Time (TBT)
• Speed Index
• Time to Interactive (TTI)
• Cumulative Layout Shift (CLS) (again, measured in a lab setting)

You’ll also see the overall performance score (1–100) in this section.

Why it can be misleading

Because lab data is simulated, it can’t distinguish between your site content and third-party code, such as ads or analytics. As a result:

• Raptive ad scripts may appear as “render-blocking” or “unused JavaScript.”
• PSI may flag ad scripts under Opportunities → Reduce unused JavaScript or Diagnostics → Reduce the impact of third-party code.

These warnings are expected and not indicative of real-world issues. Lab tools analyze everything together, so asynchronous code is often incorrectly flagged as blocking when it actually isn’t.

Why lab data matters

Although it doesn’t directly affect SEO or Core Web Vitals, lab data is a valuable diagnostic tool. It helps developers identify potential bottlenecks, large render-blocking resources, or inefficient scripts that could impact initial load performance. Use lab data for troubleshooting and optimization testing, but always validate improvements using field data, since that’s what Google and users rely on.

Raptive ads and site speed

Raptive’s ad technology is engineered to prioritize your site’s content and protect real-world performance.

Asynchronous Loading: How It Works

All Raptive ad scripts and related resources are loaded asynchronously, which means:

• Your site’s main content loads first, allowing readers to view and interact with your page almost immediately.
• Ad requests and bidding scripts load in the background, without delaying your content.
• This approach ensures that ads do not interfere with LCP, INP, or CLS, which are the metrics that matter for rankings and user experience.

This design ensures that your field data remains accurate and strong, even if lab data reports ad-related “issues.”

Common PSI observations

In PageSpeed Insights, you may see Raptive or ad-related scripts listed under:

• Opportunities → Reduce unused JavaScript

• Diagnostics → Reduce the impact of third-party code

These are normal and expected. They appear because PSI’s lab tests run in isolation and treat every script equally — even those that are delayed or asynchronous.

Deferring Raptive ad code

We do not recommend delaying the Raptive ad code within a WordPress optimization plugin. Doing so can negatively impact your earnings and email identity solutions.

For those who want to improve Lab Data scores, Raptive offers an optional deferred ad loading feature, which further delays the loading of ad scripts.

Raptive's deferred ad loading can reduce RPM by 0.5–1% and is not typically recommended unless there’s a specific need to boost simulated lab scores. Contact us if you’d like to turn on Raptive’s deferred ad loading for your site.

Field data vs lab data - the key difference