Mozilla is cracking down on Firefox add-ons that put an undue drag on the performance of the open source browser.
With a blog post on Friday, Mozilla said that within the next two weeks, it will add a warning to any add-on that slows Firefox's startup time by more than 25 per cent, and in an upcoming version of the browser, third-party add-ons will not be installed unless the user specifically approves the installation.
"It’s an all-too-common practice of third-party software to install toolbars and other bundled add-ons in your browser without permission," Mozilla says. "We know that these add-ons account for many of the performance problems reported to us, and users often don’t know how the add-on got there or how to remove it." Requiring approval for the installation of all add-ons, Mozilla believes, will have a "huge impact" on performance.
Every week, Mozilla will run automated performance tests on the top 100 add-ons in its add-on gallery, and it will display the results here. After the first round of tests, the slowest performing add-on is the hugely popular website debugger, Firebug. According to Mozilla's stats, Firebug slows startup by 75 per cent.
The seventh slowest add-on is FastestFox. It's designed for speedy browsing, but it slows startup time by 31 per cent.
In the coming months, Mozilla will also provide tools to developers that will let them test add-on performance on their own, and it will be contacting developers whose add-ons are putting an inordinate drag on startup time.
"Firefox performance is extremely important to our users, especially how quickly it starts up and loads websites," Mozilla says. "Customization is also extremely important, and while most add-ons cause only a tiny performance impact, others can significantly slow down Firefox. Many users don’t realize add-ons can cause these delays, and that’s why we’re committed to improving performance in a big way."
Eventually, Mozilla says, it will test all add-ons as they're submitted to the gallery, and it will expand testing to page load time. ®