In June 2021 Google began rolling out its Core Web Vitals (CWV) page experience update. Built to monitor and enhance the user experience, this development could impact publisher revenues. Although it’s too early to define how significant the impact will be, Google’s unusually transparent approach to this algorithm update means publishers can seize the opportunity to adapt. 

So, what specific changes does this entail and how can publishers best respond?

Google’s Core Web Vitals 101

In essence, Google has selected three signals from page speed metrics which measure a web page’s performance as it relates to user experience. As a result of optimising performance against these three metrics, publisher sites will achieve increased rankings through Google’s algorithm. 

With a focus on loading time, visual stability, and interactivity, Google’s CWV reports enable publishers to learn which elements of web pages affect the user experience. Here’s a closer look at each signal:

  • Largest Contentful Paint (LCP): This metric allows publishers to measure the time needed for a page’s main content to load, such as the largest image or text block on a user’s screen. The smaller the time window between this moment and when the page starts loading, the better LCP publishers will have. An optimal LCP score should be 2.5 seconds or less.
  • Cumulative Layout Shift (CLS): Designed to ensure a page’s visual stability, CLS evaluates how often users witness an unexpected shift in layout. A number of factors can play into this, for instance loading visual elements of unknown sizes, third-party ads without fixed dimensions, or dynamic content. As CLS aims to minimise the disruption layout shifts cause, publishers should aim for a CLS score of 0.1 or less.
  • First Input Delay (FID): A page’s interactivity is also a key factor in the user experience, so FID assesses the time between a user interacting with a page and  when it begins to respond. FID quantifies usability and supports publishers with improving responsiveness — whether that’s a user clicking a link or expanding a video player. Ideally, publishers should have an FID of no more than 100 milliseconds.

With a stronger understanding of Google’s mandate to improve page performance, what actions can publishers take to meet these standards?

How publishers should respond to the CWV update:

Staying on the right side of Google’s algorithm helps protect publisher revenues, as it can sustain and increase rankings. While numerous elements contribute to enhancing the CWV metrics, it will be critical to address how digital ads influence the user experience. Publishers should account for how and where ads appear, to reduce page load times and layout shifts. Following these tips, publishers can improve their scores:

Determine fixed ad sizes 

A common cause of layout shifts is from programmatic auctions serving ads of varying heights. When the ads load, they move users to a different part of the page and this leads to frustration, potentially causing them to not return. Although enabling ads of different sizes can drive revenue, publishers can minimise CLS issues by allocating space for the maximum ad height, then ensuring the refresh logic consistently serves ads of that height throughout the user’s time spent on a page. 

Experiment with sticky ads 

Whether placed in the header, footer, or sidebar, sticky ads maintain their position in a user’s viewport as they scroll through a web page. Sticky ads’ primary advantage is that they don’t cause layout shifts and boost a publisher’s CLS score. What’s more, the ad always stays in view, ensuring users are exposed irrespective of the device they use or their behaviour on the page. Using sticky ads, publishers can improve CPMs and refresh ads within the limits of their demand platform policies to generate greater revenue. 

Leverage lazy loading 

Another impact ads have on page performance is increasing load times. To minimise this and safeguard the user experience, publishers can implement lazy loading for ads — but specifically for those below the fold. This practice works by only prompting ads to load when users are 500 pixels away from seeing it on the page, creating a streamlined experience as they continue scrolling. Lazy loading ads also has an added benefit of increasing viewability for those ads. 

 Pay attention to ad density 

Ad density is quantified by dividing the sum of all ads’ height by the height of a user’s viewport. According to Google, ad density should sit at less than 30%, as research shows that surpassing this percentage will have negative consequences on the user experience. To keep ad density within acceptable levels, publishers can reduce the size of ads or position them further apart on a page. 

Google’s CWV update may require some consideration from publishers, but ultimately, its goal is to improve the user experience. As this is an integral part of publishers’ revenue strategies, it will be in their best interests to leverage the new metrics and implement any relevant changes to their page performance. More satisfied users will generate longer dwell times, better audience retention, and stronger reputations for publishers, which in turn will boost their bottom lines.