Well if the computer is THAT weak, then I suggest you throw Linux on it and get a new computer. I have an old HP laptop which has a piece of shit Atom processor in it and 80GB HDD, slow as shit, freezing in Windows XP all the time as soon as you open 3 Firefox tabs.
Eventually I threw Fedora 32bit on it with XFCE and now it's at least usable for normal tasks.