Even if you don't require much of these computers, you would notice a significant increase in processing speed if you removed Norton and replaced it with another a/v program.
One of the problems with Norton, is that it's constantly calling home, checking for updates. At least that's how it used to operate. I haven't used it in over five years now, so maybe they changed that.
Still, I've had nothing but trouble with everything labeled Symantec. Over time, I've deleted every file I could find in my computer related to their software, with resultant improved performance.
<it’s constantly calling home, checking for updates
Well, that’s no lie. Apparently nothing’s changed there. It is a pain.