Python’s JIT compiler has been experimental since Python 3.13, but Python 3.15 is an important step in its development. The first release candidate, Python 3.15.0rc1, was released on August 4, 2026 , with the final release expected in October. The main change is not simply the presence of a JIT, but a substantial improvement in how it observes and optimizes Python code. A New Tracing Frontend The 3.15 JIT now uses a new tracing frontend that records the execution paths a progr...