Understanding Google Chrome’s Heavy Ad Intervention

The past several years have seen an increased focus on ad specs and behavior, in particular from organizations like the IAB and big tech businesses like Google. This is part of the ongoing fight for ad quality, taking place on three fronts: security, ad content (including inappropriate, off-brand, irrelevant, or otherwise undesirable content), and ad specs/behavior.

When it comes to heavy ad monitoring and prevention, the consequences of inaction can be costly to publishers. Whether or not these ads are served in good faith, digital publishers need to take measures to avoid heavy ads so that they can continue earning revenue from their website and ad partners remain satisfied.

What Are Heavy Ads?

Google standards determine that any ad that uses more than 15-seconds of CPU in a 30-second span or has total CPU usage of more than 60 seconds or 4MB is a heavy ad.

In 2019, Google set standards for heavy ads that included two criteria.

1) An ad may use no more than 15 seconds of CPU within a 30-second span.

2) Total CPU usage for an ad can total no more than 60 seconds and no more than 4MB of network data.

In general, if an ad exceeds that limit, and there has been no user interaction, Chrome will block the ad and serve an error message in the ad unit. Google has also published more granular guidance for Javascript and other types of developers.

Google set this heavy ad criteria after researching and testing ad performance and discovering that 0.3% of all digital ads are responsible for using 27% of network data and 28% of CPU usage among all ads in the ecosystem. IAB Lean issued similar guidance. Extensive testing has shown that following the heavy ad guidelines allows web pages to load faster on any device, preserves carriers’ network usage bandwidth, limits users’ data overages, and even discourages crypto-mining attacks.

Heavy Ads Cause Problems for Users

Heavy ads can cause a page to be slow to load, make a device shut down mid-session, or lead to excessive data usage and overage charges.

Many ad security threats and low-quality content ads come from overtly malicious actors. However, ads that compromise page performance or the device’s resources are more of a mixed bag. Some are part of crypto-mining schemes or arbitrage strategies. Others are simply coded poorly or are not optimized for battery or data usage.

Heavy ads can be insidious because a user won’t necessarily recognize that poor site performance could be anything beyond a mild inconvenience. It’s easy to notice when a page is slow to load. But it’s more difficult to detect right away when too many resources are being used — excessive CPU or data usage for example. The noticeable impact of heavy ads often includes less obvious things like devices shutting down mid-session and overage charges. This often leads users to make the incorrect assumption that their device needs to be serviced and remain unaware of the actual problem.

Learn More Here

What Is Heavy Ad Intervention?

Heavy ad intervention includes any feature or reporting API that lets publishers, ad partners, or users know that heavy ads may be impacting the performance of their web content. It also includes tools that assist in blocking heavy ads.

Why The Industry Needs Heavy Ad Intervention

Heavy ad intervention (HAI) is necessary to block resource-straining ads before they impact the user experience.

HAI is necessary because communication breakdowns and security lapses along the ad supply chain are ultimately unavoidable without robust, real-time ad quality tools. Therefore, in 2020, Google introduced Heavy Ad Intervention (HAI) to enforce its heavy ad policies and trigger better heavy ad interventions on the Chrome browser. HAI replaces a heavy ad with an “ad removed” message and a link the user can follow for details. It is a helpful way to deliver a safe browsing and ad experience and encourage user engagement, benefitting publishers and advertisers alike.

This intervention aims to block resource-straining ads such as malicious crypto-mining attacks, improperly compressed images, and in-banner videos shown in the Chrome browser and browsers. The initiative was based on IAB Lean protocol, along with insights from the heaviest .01% of ads seen on the Chrome browser.

Publishers, however, need to use a report mechanism in order to know if Chrome removed ads on one of their websites. Google does offer a reporting API that allows publishers to set a reporting endpoints header in the HTTP response. Once this has been set up, the publisher can see an error page report for endpoints and can take action to enable heavy ad intervention.

How HAI Impacts Publishers’ Business

HAI can prevent a loss of user engagement and bad user experience on the publisher’s website.

While Google’s solution is a type of heavy ad intervention, it isn’t ideal for publishers. An error note can disrupt a site’s overall feel and brand, and can lead users to suspect that publishers have partnered with shady ad partners or simply have low standards for the content they host on the page. Mistrust causes users to avoid a site and prevents the publisher from monetizing the user’s lifetime value.

When a heavy ad causes a page to load slowly or freeze, the impact is immediate. Research shows 47% of users will stop engaging with content if they think it’s taking too long to load. On mobile, increasing page load from just one to three seconds makes a user 32% more likely to stop engaging.

How To Block Heavy Ads

Google HAI isn’t enough. Publishers need ad quality tools specifically designed to protect their inventory from revenue-threatening heavy ads.

Good communication along the supply chain isn’t enough to keep all heavy ads off a page. Think back to when Flash was being phased out — for years, publishers continued getting Flash ad content, regardless of publisher specs and industry guidance.

There are preventive measures publishers can take, although they are not all equally reliable. For example, Google offers resources for developers to test HAI on their sites. A publisher’s team can use it to select ad content and see any “ad removed” messages HAI would have displayed.

However, Google launched HAI before the programmatic ecosystem was equipped to report on it. According to industry insiders, as of the summer of 2021, it appears that no ad servers can report on HAI-blocked ads. Google’s advice to publishers is that they don’t need to take special measures with ads from third-party sources — as long as they bear in mind that heavy ads will trigger an “ad removed” error message.

There’s no consensus on the share of heavy ads blocked because of data and network bandwidth versus CPU drain. There’s also no agreement as to whether heavy ads are more likely to come from programmatic or direct advertising. Moreover, crypto-mining attacks often come through broad ad content verticals. GeoEdge has found that the most egregious heavy ads, including ads that use up to 75% of CPU, come through the “internet” content category. Since spot checking is such an ineffective strategy, publishers must consider ad quality tools specifically designed to protect all their inventory from disruptive and revenue-threatening heavy ads.

Navigating HAI Reporting 

Publishers should communicate specs to demand partners, and also adopt efficient, reliable solutions designed for HAI.

Publishers should always communicate their own specs for every site and post request, along with broader industry standards, to their demand partners. For example, demand partners should always ensure all Javascript is well-written and complies with Google’s guidelines for animations. Publishers should, however, be aware and expect that heavy ads will still come along, and that they’ll be blocked, one way or another.

That’s why publishers need to take control over their inventory and reporting to prevent user experience and revenue from being compromised by heavy ads and error messages on their website. A reporting API isn’t enough. They need an ad-quality solution that can enable heavy ad intervention is efficient and consistently reliable.

Try Our Tools For Free

Alisha is a Technology Writer and Marketing Manager at GeoEdge. Her writing focuses on current events in the AdTech ecosystem and cyberattacks served through the digital advertising supply chain. You can find Alisha on LinkedIn to discuss brand building and happenings in AdTech.

Malvertising, the practice of sprinkling malicious code into legitimate-looking ads is growing more sophisticated. GeoEdge’s holistic ad quality solution has you covered.


450+ Publishers & Platforms