Hello friend, the appearance of more than 1 browser function is completely normal, it is because it works with tabs, I give you my case, at this moment, I have the browser with 8 active tabs and in processes I have 15 chrome, the problem is that If you are not downloading anything or loading a page, the CPU consumption should be minimal, I leave a fire fox support link that is what I see that you use, so that you go there, but also tell you that you can have a virus in the Navigator. https://support.mozilla.org/es/kb/Firefox%20consume%20demasiados%20recursos%20de%20la%20CPU