Longtime PyPy developer Antonio Cuni has a lengthy blog post that describes his talk at the recently completed 2025 CPython Core Dev Sprint, held at Arm in Cambridge, UK. The talk, entitled "Tracing JIT and real world Python — aka: what we can learn from PyPy" was meant to try to pass on some of his experiences "optimizing existing code for PyPy at a high-frequency trading firm" to the developers working on the CPython JIT compiler. His goal was to raise awareness of some of the problems he...