Comment by haberman

Good to know! Thanks for confirming. Yes, I would guess that the tail call interpreter explains part of the difference between 3.13 and 3.14. Previously the overall improvement to the interpreter has been measured at 1-5%, or even 10-15% depending on the compiler version you are using: https://blog.nelhage.com/post/cpython-tail-call/

If your benchmark setup is easy to re-run, it would be awesome to see numbers that compare the tail call interpreter to the build where it is disabled, to isolate how much improvement is due to that.