I have been enjoying the recent threads by @pervognsen about instruction-level efficiency on computers over the years, so I'm going to do a brief one of my own based on some of my recent adventures.
It'll end up touching on topics that are coming up today and on some conversations I'd had some years ago.
In 2018, I wrote a cellular automaton program for the Sega Genesis (8MHz 68000 CPU), and in 2023 I wrote a version for the SNES (3-ish MHz 65816 CPU).