Python Insider: Python 3.15.0 alpha 6

Python 3.15.0 alpha 6 is now available for testing. Key features include a new high-frequency statistical sampling profiler (PEP 799), unpacking in comprehensions, UTF-8 as default encoding, and significant JIT compiler upgrades delivering 3-4% performance improvement on x86-64 Linux and 7-8% on AArch64 macOS. Additional improvements include TypedDict with typed extra items, a new PyBytesWriter C API, and enhanced error messages. The beta phase begins May 5, 2026, with the next alpha release scheduled for March 10, 2026.