Cinnamon uses slightly more resources than the other two. But, it's lightweight enough I doubt you are going to have an issue, even with a computer of that era.

I’d say RAM is going to be the largest performance bottle neck for a desktop environment on an older machine. 4gb of RAM? don’t bother with cinnamon, you’ll likely have a much better experience with Mate or XFCE. 8gb is about where I’d even bother to test out cinnamon.

You should probably take a look into puppy Linux, if low specs. Otherwise anything with xfce should run better on it.

Hard to say without specs. I'd go with XFCE and then MATE right behind it. With a lower end PC, I doubt it could handle the fanciness of Cinnamon and still run software