Original link: Despite 30 months work, core developer says Python’s JIT compiler is often slower than the interpreter / DevClass.
Quotes:
The JIT compiler is included in Python 3.13, released in October 2024, but only when CPython is built using the –enable-experimental-jit option. Early reports spoke of a speed-up of between 2 and 9 percent; but Jin said that “it’s really more nuanced than that. Often times, the CPython 3.13 JIT is a lot slower than the interpreter.”
Another complication is that the performance of CPython varies according to the compiler used to build it. When it is built using a modern compiler like Clang 20, Jin said, the interpreter often out-performs the JIT. If an old compiler like GCC 11 is used though, the JIT may be equal or faster than the interpreter.