Which is more efficient recursion or loops?

Which is more efficient recursion or loops?

I am curious which is more efficient for iteration. I am using one to
break up a parse a string into a List. Is recursion more CPU efficient or
is looping? Is either more memory efficient? By looping, I am referring to
for, for each, do while, while, and any other types. Out of these loops
which are more efficient? Or are they all equally? Just curious.