Why are dynamically typed languages slow?

Question

What makes it hard to speed up dynamically typed languages when compared to statically typed languages . In other words what is inherent property of statically typed languag

Answer 1

Look at this python example:

def fact(n):
    if n==0:
        return n
    return n*fact(n-1)

What is n? Is it a number? Is it a String? Is it a class you defined earlier? There is no way for the compiler to know what input it will get. You have to do a lot of checking at run-time, which means that you are doing more implicit work for simple operations.