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[Update: Flags] Google is developing a ‘heavy ad’ blocker for Chrome [Gallery]

While ads essentially fund the internet as we know it today, sometimes they can create some of the worst experiences that the web has to offer. Google is working on a way for Chrome to automatically block some “heavy ads” on the web, that tend to slow down our browsers.

Google has been back and forth on ad blocking in the last few years. Most recently, the company was in hot water due to upcoming changes to the way ad blocking Chrome extensions are required to work. Before that though, Google developed a built-in ad blocker for Chrome, designed to exclusively handle ads that Google doesn’t consider to be in-line with the Better Ads Standards.

Judging from a work-in-progress Chromium commit, the Chrome team may be expanding on this effort with a new blocker that targets ads that use too much network or CPU, or, as Google calls them, “heavy ads.” The commit message shares some specifics on what it currently takes to trigger this blocker, but notes that these numbers are subject to change at any time.

This intervention unloads ads that are in the .1% of bandwidth usage, .1% of CPU usage per minute, and .1% of overall CPU time. The current numbers are 4MB network and 60 seconds CPU, but may be changed as more data is available.

Where Chrome’s existing ad blocker eliminates the ads for an entire page, the new “heavy ad” blocker specifically only handles the problem ad. Heavy ads are replaced in the page with a notice of the removal and a “Details” button you can click to learn more. We managed to get an early preview of this notice.

Beyond this little bit, there’s not much info on Chrome’s heavy ad blocker, such as when we can expect to see it arrive on devices. As work is only just beginning now, it will surely be a number of months before Google would be able to launch it. And just like everything else we find in Chromium source, Google may decide to scrap the project altogether before it sees the light of day.

Update 10/30: The folks at Techdows have spotted that Google has added two flags related to Chrome’s “heavy ad” blocker. The first flag simply enables/disables the heavy ad blocker.

Heavy Ad Intervention

Unloads ads that use too many device resources.


The second flag allows you to disable the blocker’s built-in privacy protections, for debugging purposes. The protections prevent malicious ads from learning details about your computer/network based on when Chrome “unloads” a heavy ad. For a more technical explanation about how these privacy protections work, check out the official explainer.

Disable heavy ad privacy mitigations

Disables privacy mitigations for the heavy ad intervention. This makes the intervention deterministic. This is intended to be used for debugging only.


As the flags are only just now appearing in the most recent Chrome Canary builds, the heavy ad blocker likely won’t launch any sooner than Chrome 80.

9to5Google’s Take

Managing ads is a tricky balance for Google. As the developers of Chrome, one of the world’s top browsers, they’re obligated to improve the user experience by removing malicious ads and now “heavy” ads. However, as the company responsible for AdWords and AdSense, Google can’t make moves that could be perceived as too heavy-handed toward other advertising companies, as this could be considered anti-competitive behavior.

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Avatar for Kyle Bradshaw Kyle Bradshaw

Kyle is an author and researcher for 9to5Google, with special interests in Made by Google products, Fuchsia, and Stadia.

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