i heard the newest version of ubuntu doesn't work very well on computers that are 4 years old and older, does linux-mint 18.3 have similar issues?

According the minimum system specs, this should be right inline with what you need (depending on the specs of the CPU, they recommend a 2.0 GHz Dual Core). Graphics are the biggest issue with the newer distros. Ubuntu is using Gnome Shell now, which is better than what they had, but it may need some tweaking down the graphics. You can check the minimums from Ubuntu here: https://help.ubuntu.com/commun ... ments
The best thing to do is try to run in live through a live boot disk or drive and see how it works with your hardware, before installing.