Perhaps the specific websites you are using are particularly bad on Firefox (whether due to issues with the website or Firefox), but I do not share your experie

Perhaps the specific websites you are using are particularly bad on Firefox (whether due to issues with the website or Firefox), but I do not share your experience at all. For me Firefox is fast and I never see it using too much memory, much less bringing the whole system to a halt. So my suggestion is to file bugs for any websites that perform particularly badly for you.