In May Google announced major upcoming 2021 changes to its search ranking algorithm, including the addition of Core Web Vitals, which are new metrics related to page load times and the jumpiness of content.
Cumulative Layout Shift measures the stability of the page load: do the content and images move around before the page finishes rendering? Google recommends a CLS score of no more than 0.1 (using an equation based on content size and distance moved).
Largest Contentful Paint looks at overall loading performance of the main content. Does everything load within the recommended 2.5 seconds?
First Input Delay analyzes how network requests slow down the main thread - i.e., do slow-to-load requests prevent the user from clicking on a link? Google recommends an FID of less than 100ms.
One byproduct of programmatic ads, especially with complex header-bidding setups or an overloading of ad units, is slow-to-load, jumpy content. Publishers generally accept this suboptimal user experience because of the ad revenue that comes with it.
If ads lead to poor Core Web Vital scores, then it’s possible these slow ad experiences could do more than frustrate users: they could also hurt SEO efforts.
And with Google search being such a heavy traffic driver for many sites, even a small dip in rankings could have a sizable impact on top-line revenue and page views.
It's imperative, then, that publishers are aware of their ad set-ups and not employing an ad strategy that could end up lowering their revenue in 2021.
This is easy to test with the Google Chrome browser and its built-in Lighthouse dev tool, which will refresh a page and return two of the three core web vital scores (CLS and LCP).
I did this across four high-volume sites, all of which show multiple programmatic ads on their homepages, including a top-of-page leaderboard ad. I ran the Lighthouse report multiple times, with and without an ad blocker, and below are the average scores.
Cumulative Layout Shift: this looks at the jumpiness of the page load. The ideal score is < 0.1, using an equation based on content size and distance moved.
Largest Contentful Paint: this looks at overall load speed of the main content. Target score is < 2.5 seconds.
These results suggest that programmatic ads do indeed hurt Core Web Vitals scores.
For instance, while three of the four sites were still above the 2.5 second target without ads, when ads were enabled LCP increased by 1.5 seconds on average. In other words, by enabling top-of-page ads on their site, these brands saw their LCP scores jump (aka, worsen) by 30%-45%.
This is a very small sample size, of course, and the test quite unscientific, but the results nonetheless suggest that ads do decrease Core Web Vitals scores, which, in turn, could impact search rankings in 2021.
It’s important not to overreact here. Google has already stated that quality content supersedes these metrics, and we don’t know how much weight PageRank will give them (it could be close to zero).
This could lead to few potential scenarios:
Indeed, there are so many industry changes that are signaling a crisis for programmatic advertising in general, including GDPR/CCPA/other privacy laws, the deprecation of third-party cookies, mobile IDs going away, ad fraud concerns, and a growing awareness of ad tech middleman fees (about 50%).
No matter what, publishers should monitor their Core Web Vitals in the coming year. Even small downgrades to one’s search rankings can have a sizable impact on traffic and revenue. The update isn’t going live until 2021 – and developers can do their own testing with Chrome well before then.
Disclaimer: a similar article originally appeared on 7/31/2020 in AdExchanger
Chris has worked in ad tech for over fourteen years in a variety of roles - giving him customer support, PM, and marketing perspectives from both the advertiser and publisher sides. He's the VP of Marketing at Kevel.