Why recursive function consumes more of processing time than loops?

[M83Linux]

Hi All,

Why recursive function consumes more processing time than loops?
And, Is it cumbersome for the processor?

def fibonacci(n):
    if n == 0:
        return 0
    elif n == 1:
        return 1
    else:
        return fibonacci(n-1) + fibonacci(n-2)

print fibonacci(40)

^^^^ this example takes about 1 min, but with loop only few ms