I set up two old computers to play some Minecraft with my youngest kid. Unfortunately it turns out recent versions are much slower than old ones. I have not bothered to bisect it to figure out exactly what version(s) killed performance. My weakest old computer can run the latest version with 1-2 fps. It can run 1.12 with at least around 30-40 fps, which is more than enough for me to be able to enjoy the game (being old enough to have grown up in an era when we were happily playing flight sims at 5-10 fps). Anyway it is nice that the launcher makes it possible and easy to go back and play older versions. I much prefer drm-free games, but at least supporting old versions like this is better than 99% of games.