Feature freeze for Python 3.15 as first beta released

"The Python team has released the first beta of version 3.15, with new features including a stable application binary interface (ABI) for free-threaded CPython, lazy imports to speed startup time, a new zero-overhead sampling profiler, use of UTF-8 text encoding by default, and a faster just-in-time (JIT) compiler."

"The option to remove the global interpreter lock (GIL), available in Python 3.14, was the biggest change to Python for years, enabling efficient concurrency on multi-core CPUs. The new stable ABI means that C extensions can now be compiled for multiple minor versions of free-threaded builds, though the team warns that doing so means only a subset of the full CPython API is available. The existing stable ABI remains available, and it is possible to compile for both."

"Explicit lazy imports can improve startup time for Python applications by deferring module loading until it is first accessed. Otherwise, an imported module is loaded and compiled to bytecode immediately - though developers could use workarounds at the expense of code readability. The solution for this is a new keyword: lazy import json"

"A new sampling profiler called Tachyon works by capturing stack traces from running processes, instead of instrumenting function calls. According to the docs, the approach "provides virtually zero overhead while achieving sampling rates of up to 1,000,000 Hz" and can be used to debug performance issues in production."

Python 3.15 beta introduces a stable ABI for free-threaded CPython, enabling C extensions to target multiple minor versions of free-threaded builds while limiting access to a subset of the full CPython API. Lazy imports improve startup time by deferring module loading and bytecode compilation until first access, with a new keyword to express this behavior. A new sampling profiler, Tachyon, captures stack traces from running processes rather than instrumenting function calls, aiming for virtually zero overhead with very high sampling rates. Python 3.15 defaults to UTF-8 text encoding, while explicit encoding remains recommended for compatibility. The JIT compiler is faster, and there is no reinstatement for a leaky incremental garbage collector.

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