Adblockers Performance Study
&gt; This work was motivated by one of the claims formulated in the Manifest V3 proposal of the Chromium project: &quot;the extension then performs arbitrary (and potentially very slow) JavaScript&quot;, talking about content-blockers&#x27; ability to process all network requests. From the measurements, we do not think this claim holds, as all popular content-blockers are already very efficient and should not incur any noticeable slow-down for users.<p>There&#x27;s a few issues with the conclusion here. First, they article measures and discusses only the time required to block a single request. Modern web pages are issuing many, many more requests than that, like the 35 that this page issues. At median timings, that would put the DuckDuckGo blocker at almost 300ms, well within what humans can notice.<p>The second is that this API is not used solely by the popular content blocking extensions, but by a variety of other extensions. The Chome team&#x27;s performance concerns likely stem from the fact that a user won&#x27;t be able to differentiate the browser slowing down and an errant extension slowing down the network requests, and there are  examples of extensions that use this API to issue additional network requests or do slow things down. If you cherry-pick the good citizens of this API to show that performance isn&#x27;t a problem in general, you&#x27;re not showing that performance can&#x27;t or shouldn&#x27;t be the reason, just that it isn&#x27;t the reason for the fast good citizens. What this data could be used to argue is that imposing strict deadlines on the execution time of these extensions would allow the content blockers that the community cares about to continue to function as they do today while also placing a performance cap on bad extensions.