Python 3.14 ships with a JIT compiler now included in official installers (Windows .msi and macOS .pkg), no longer requiring manual compilation from source. The JIT uses a copy-and-patch technique and a three-tier system: standard interpretation, specialised bytecode (from 3.11), and machine code generation for hot paths. It is disabled by default and enabled via the PYTHON_JIT=1 environment variable. Benchmarks on CPU-bound pure Python workloads (Mandelbrot, Levenshtein) show 24–27% speedups, while heap/allocation-heavy code like Dijkstra sees no meaningful gain. The JIT is most beneficial for long-running CPU-bound processes and least useful for I/O-bound apps, short-lived scripts, or memory-constrained environments. Python 3.15+ is expected to bring deeper optimisation passes and smarter warm-up heuristics.
