fib := method(n,
  if(n <= 0) then(
    return 0
  ) elseif(n == 1) then(
    return 1
  ) else (
    return fib(n-1) + fib(n-2)
  )
)

fib(30) println

# time of fib(30)
# real    0m5.420s
# user    0m5.394s
# sys     0m0.020s