One of the faq things refers in passing to integers being 64bit instead of arbitrary precision. That's a bit more fundamental than some cpython modules don't work. Haven't found a language reference yet.
edit: it's statically typed ahead of time - that feels like something that needs a detailed description of what it's doing, given the baseline of like-python
It would cause major issues to libraries for mathematics (such as sympy or sagemath) that assume integers are arbitrary precision. Large integers are common in number theory and cryptography, where people also care very much about performance.
