"You can poke new values into the start-of-program pointer to speed up jumps to the end of the program, and speed up loop execution" is pretty tricky. So's "you can poke new values into another pointer to jump to arbitrary statements within a multi-statement line, and here[1] is a 3d maze program that abuses the heck out of this to become a one-liner".

1: https://spectrumcomputing.co.uk/entry/21001/ZX-Spectrum/1_Li...