The list is just one part of Mozilla’s new efforts to highlight slow add-ons, and to help developers make their add-ons more efficient. Over the next two weeks, ‘slow performance warnings’ will be introduced in the add-on gallery so that users can see, before installation, which add-ons will slow down their browser. If that isn’t enough to spur developers into cleaning up their add-ons, Mozilla has also begun reaching out to developers of slow add-ons with tips on how to improve add-on performance. Finally, add-on developers will soon have the ability to perform ‘on-demand performance testing,’ so that they can test their add-on before it’s deployed publicly.
Mozilla reports that the average Firefox add-on slows down Firefox’s start-up time by 10% — which means, if you install 10 add-ons, you will double your start-up time. On fast desktop PCs that kind of slowdown might be negligible, but on older computers, laptops and smartphones, it could be the difference between a 5 and 10 second startup. Mozilla has obviously realized that while massive performance gains might’ve been made with Firefox 4, the addition of third-party add-ons can destroy any user-perceived improvements.
In other news, Mozilla says that a future build of Firefox will block the installation of add-ons (such as toolbars) by third-party software. Add-ons and toolbars that are bundled in this way will require explicit approval when you next open up Firefox. Hooray!