Python 3.15 ships: default UTF-8, lazy imports, JIT 12% faster, Tachyon profiler
charliermarsh · x · 2026-10-10
Python 3.15.0 is out with 5,643 commits from 1,012 contributors. Highlights: UTF-8 becomes the default encoding (PEP 686), explicit lazy imports for faster startup (PEP 810), built-in sentinel and frozendict types, comprehension unpacking (PEP 798). The experimental JIT compiler now delivers a 7-8% geometric mean speedup on x86-64 Linux and 11-12% on AArch64 macOS. A new profiling package with the high-frequency sampling profiler Tachyon lands in the stdlib, alongside new typing features (TypedDict extra items, TypeForm, disjoint bases) and C API improvements including stable ABI for free-threaded builds.
Related event: Python 3.15 Released, uv 0.13.0 Adds Same-Day Support(3 posts)→
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