Just over a week ago we announced our add-on performance initiative and have received lots of feedback from add-on users and developers. Thanks to our awesome community, many developers have updated their add-ons to have faster start-up time, and others have dug into the results and filed bugs to help us improve our testing framework. Our automated tests don’t work perfectly with every add-on, so if you aren’t able to reproduce our results, please file a bug and let us know.
One of the most popular components of our performance initiative is the Slow Performing Add-ons page. We’ve made some changes to the page to more accurately describe the performance results shown and hide add-ons that have minimal impact on performance from being included in the list. Now, only add-ons with an impact of 25% or more are displayed instead of an ordered list of all add-ons tested. Additionally, we’ve corrected some wording that referred to these add-ons as the “slowest”. We apologize for this oversight.
We initially planned to begin displaying warnings for add-ons that add more than 25% to start-up time this week, but will delay that until we can verify and fix any major issues discovered by the community. However, all of the add-ons currently displayed on the page have been verified as causing a significant impact on Firefox start-up through manual testing and real-world data, in addition to the automated testing.
As we said in the announcement, this is only the beginning of our work to improve and educate about add-on performance, and we’ll continue improving our tools and documentation to help developers.