Function call is a well-known weak point of cpython, even amongst all its other weak points performance-wise.

It's hard to express how utterly uninteresting and useless TFA is, and if its author is surprised by the result… really the only component this tells us about is the author.

> Would be much more interesting to compare to pypy.

I'm not sure it is more interesting at all, let alone much more, but here are the results on my (obviously much slower than TFA's) machine:

    > python3.9 --version
    Python 3.9.1
    > python3.9 fib.py
    8555.904865264893 ms
    > pypy37 --version
    Python 3.7.9 (7e6e2bb30ac5fbdbd443619cae28c51d5c162a02, Jan 15 2021, 06:03:20)
    [PyPy 7.3.3-beta0 with GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.42.1)]
    > pypy37 fib.py
    715.0719165802002 ms
    > node --version
    v14.15.4
    > node fib.js
    247.19056797027588 ms