The CPython 3.14 change log describes the feature as “a new type of interpreter based on tail calls.” This description may be a little misleading for those who don’t closely follow internal Python development work. “Tail calls” doesn’t mean that CPython, or the Python language, will now support tail call optimization. It refers to an optimization that a C compiler performs on the CPython code, which speeds up the way the interpreter dispatches its bytecode instructions.