This talk is a follow-up to my EuroPython 2025 session on the foundations of the CPython JIT compiler. It looks at how the JIT has evolved since Python 3.14 and where it stands as Python 3.15 approaches release. We cover the transition of the JIT from an experimental feature towards a supported part of CPython, how it fits into the runtime today, and what that means in practice for users and distributors. The talk also explores how the JIT interacts with free-threaded builds, the current status of integration with external debuggers, and how these constraints shape real-world usage. Finally, we examine how the JIT performs today, where it already delivers substantial speedups, where it does not, and what realistic performance expectations look like for Python 3.15.

Running Python natively on Windows on Arm requires more than a working interpreter. To have a nice developer experience, it depends on compilers, packaging, binary wheels, CI infrastructure, and support from the wider library ecosystem.

This talk provides a status update of the Python ecosystem on Windows on Arm in 2026, based on ongoing collaboration between Microsoft, Arm, and the open-source community. We will cover CPython support, packaging, wheels, tooling, and CI availability, with a focus on what developers can realistically use today.

Using widely adopted libraries such as PyTorch as examples, we will show how native Arm support is being enabled across the ecosystem, what remaining challenges projects face when supporting Windows on Arm.

The talk will also cover the developer and CI story enabled by native Arm runners and Windows 11 Arm images on GitHub Actions, and how this infrastructure lowers the barrier for projects to add and maintain Windows on Arm support.

The goal is to give a snapshot of the current state, highlight the remaining gaps, and explain how contributors and maintainers can participate to the ongoing effort.