Optimise the Python program to reduce the time complexity for finding the maximum element in an array.
[5, 10, 15, 20]
def findMax(arr):
    max = arr[0]
    curr_max = arr[0]
    for i in arr[1:]:
        curr_max = max = max if max > i else i 
    return curr_max

print(findMax([5, 10, 15, 20]))