Loop hangs when it ends?

[Nodnarb12500]

(defvar x 0)
(loop (if (!= x 5)
          (set x (+ x 1))
      )
)

no output and slowly eats ram

(defvar x 0)
(loop (when (< x 5)
          (set x (+ x 1))
          (println x)
      )
)

after getting to the number 5 no output and slowly eats ram