Is the “older computer” slow or is it accumulated scruff (ie adware or spyware) on the Windows OS?
If the latter, you can clean that up, or load a light version of Linux like Linux Mint. That makes a big difference.
I am running Linux Xubuntu on this machine (it is not slow) and could not be more please with it.
I have an older computer too, I got rid of MacCaffey and started using the Microsoft Security Essentials that came on my computer (which was also FREE). I cannot believe how much faster my computer is now!!!
I’ve had no security problems yet - but boy, I sure did with MacCaffey - got a bad thing on there that kept popping up porn sites on my desktop - all the while my MacCaffey scans were showing no problems!
My computer runs like it did when it was new now.