In brief: Last month Google proposed changes that would have made numerous plugins, and particularly ad blockers, inoperable in Chrome, justifying the move by promising performance gains. But a new study has challenged Google’s claims of ad blockers adversely affecting performance, leading Google to backtrack on their plans.

Back in January we reported on planned API changes within Google’s Chrome browser that would have decimated the capabilities of various plugins, most notably ad blockers and antivirus extensions. At the time, Google said that such plugins were negatively affecting performance, and that by making changes to how web requests are handled, Chrome would be a faster, more efficient browser.

Developers weren’t happy with the proposed changes, and Cliqz, the makers of Ghostery ad blocker, decided to test Google’s claims.

Cliqz put together a comprehensive study looking at how popular ad blockers such as uBlock Origin, Adblock Plus and their own product Ghostery affected page loading times. It turns out that Google’s claims were bogus.

According to Cliqz, “all popular content-blockers are very efficient, having sub-millisecond median decision time per request.” They continued, saying that tested products “should not result in any over-head noticeable by users.”

Within hours of the study being published, Google put out a post of their own setting out how they’re modifying their former proposals to take note of developer feedback. In the post, Google stressed that “it is not, nor has it ever been, our goal to prevent or break content blocking” (emphasis theirs).

It appears Google have taken on board feedback pertaining to a number of aspects of their proposal to move to the new Manifest v3 standard. For example, Google had said they would limit the size of rule sets an extension could list, limiting them to 30,000 entries. Developers’ lists of rules can run into the millions, so the cut would have made such a list-based approach untenable. Similarly, their new standards had lacked functionality to block media based on conditions such as resource size – which Google has now said they will add support for.

No doubt developers will continue to scrutinize the changes, but this latest development seems like a win for extension developers and consumers alike.