Why does removing the else slow down my code?

Consider the following functions:

def fact1(n):
    if n < 2:
        return 1
    else:
        return n * fact1(n-1)

def fact2(n):
    if n < 2:
        return 1
    return n * fact2(n-1)

They should be equivalent. But there's a performance difference:

>>> T(lambda : fact1(1)).repeat(number=10000000)
[2.5754408836364746, 2.5710129737854004, 2.5678811073303223]
>>> T(lambda : fact2(1)).repeat(number=10000000)
[2.8432059288024902, 2.834425926208496, 2.8364310264587402]

The version without the else is 10% slower. This is pretty significant. Why?