Python 3.15.0 beta 4, the final planned beta before the release candidate, is now available with approximately 298 bugfixes, build improvements, and documentation changes since beta 3. Key features in Python 3.15 include PEP 810 explicit lazy imports for faster startup, a new frozendict built-in type, a sentinel built-in type, a dedicated profiling package with the Tachyon statistical sampling profiler, frame pointers enabled by default, unpacking in comprehensions, UTF-8 as the default encoding, TypedDict with typed extra items, TypeForm annotations, and a significantly upgraded JIT compiler delivering 8-9% performance improvement on x86-64 Linux and 12-13% on AArch64 macOS. The stable ABI for free-threaded builds is also included. The next pre-release will be 3.15.0rc1, scheduled for 2026-08-04. Third-party maintainers are strongly encouraged to test against this beta and report issues.
