Python 3.15.0

Python 3.15.0 was released on October 9, 2026, featuring significant performance improvements including a 7-8% speed boost on x86-64 Linux and 11-12% on AArch64 macOS through an upgraded experimental JIT compiler. The release includes major enhancements across interpreter improvements (new sentinel and frozendict types, UTF-8 default encoding, lazy imports), typing features, and C API updates, developed through 5,643 commits from 1,012 contributors. However, macOS 27.0 users should be aware of a known issue causing IDLE and tkinter-based GUI applications to hang when opening dialogs.