It doesn't matter. The user gets a bad experience and blames Firefox. "Oh, it's those naughty extensions slowing everything down!" smirk the developers. Do you

It doesn't matter. The user gets a bad experience and blames Firefox. "Oh, it's those naughty extensions slowing everything down!" smirk the developers. Do you think the user cares? Firefox is the one who opened themselves up to get abused by. (Same things happened on Windows, you'll get a machine full of crapware if you install popular apps. OSX has a curated app store. Look at the difference on an average windows and OSX machine.) Some solutions instead of blaming the user: * Name & shame poorly-performing plugins in the interface. (OSX does this with "apps using significant power" in the battery meter) * Have a plugin speed rating in the store * Have performance requirements for plugins (users will report usage data, you have X seconds to startup, if you average higher you will be reviwed/yanked.) Asking users to not install extensions when extensibility is one of your selling points is not a good idea. Fix how they interact with the browser.