CPython C API is one the main culprit in making Python hard to implement and optimize.

As some commenters said, I don't think Python without access to C/C++ projects would be worth right now giving how sloe CPython is. About 100% of machine learning, data science and general science Python code relies on C/C++ extensions.

Current CPython API and the need to keep compatibility reduces the capabilities of improving CPython.

Look at PEP-620 (https://www.python.org/dev/peps/pep-0620/) for more info on how python developers are addressing this.