Python 3.15.0 alpha 6 introduces JIT improvements and new PEPs
Key Takeaway
The sixth alpha release of Python 3.15 features significant JIT compiler performance gains and several new language enhancements.
Summary
The Python development team has released the sixth alpha version of Python 3.15. This preview includes significant upgrades to the JIT compiler, providing performance boosts on x86-64 Linux and AArch64 macOS. The release also highlights several new PEPs covering profiling, unpacking, and encoding.
Technical highlights of Python 3.15
- JIT Compiler: Achieved a 3-4% geometric mean performance improvement on x86-64 Linux and a 7-8% speedup on AArch64 macOS.
- PEP 799: Introduces a high-frequency, low-overhead statistical sampling profiler.
- PEP 798: Adds support for unpacking in comprehensions using * and **.
- PEP 686: Sets UTF-8 as the default encoding.
- PEP 782: Adds a new PyBytesWriter C API for creating bytes objects.
- PEP 728: Enables TypedDict with typed extra items.
Why it matters
As an alpha release, it allows developers to test upcoming features and the JIT compiler's performance before the beta phase begins in May 2026.
Original reference: pythoninsider.blogspot.com →