Pretty sure the issue about resources is not about one's specific PC but rather AI engine servers that waste a lot of water to cool down and being generally bad for environment. It's not about CPU, it's about Earth.
It's not optional or opt-in or whatever, that would mean it's like an extension you can add, not an already-in-just-choose-from-menu thing. Even then it would be unethical as it would be Mozilla saying "hey, if you wanna steal from others and waste r...
For all that is holy PLEASE DON'T . Generative AI wastes lots of resources, is bad for environment, steals from legitimate creators. Even if it's results are getting better (instead of the current medicore at best to straight up garbage at worst) it'...