recursion performance


Im just starting to program in lisp so please bear with me. As an
exercise, I was supposed to write the + function for 2
integers(symbols). This is what I wrote

(defun our+ (n m)
(cond
( (zerop m) n)
(t (+ (1+ n) (1- m) ) ) ) )

The suggested answer is as follows.

(defun our-add ( n m)
(cond
( (zerop m) n)
(t (1+ (our-add n (1- m) ) ) ) ) )

My question is this: Is there any difference in performance between the
first and the second?
Granted, I want to follow what the author has deemed accurate but I
dont want to do so blindly. Thanks in advance.

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