Firefox performance is extremely important to our users, especially how quickly it starts up and loads websites. 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. How slow are
![Improving Add-on Performance – Mozilla Add-ons Community Blog](https://cdn-ak-scissors.b.st-hatena.com/image/square/d47ff3e121593f6d30acd587b117a4662e1909fe/height=288;version=1;width=512/https%3A%2F%2Fblog.mozilla.org%2Faddons%2Fwp-content%2Fthemes%2FOneMozilla%2Fimg%2Fmozilla-wordmark.png)