[tantalor]

> how did they figure out the theoretical best time in the first place

A rarely used tool is brute-force searching for ideal inputs by making a computer play the game, trying all possible inputs. In theory, this process could find the ideal set of inputs for any game, but since the space of all possible inputs grows exponentially with the length of the sequence, this is only viable for optimizing very small portions of the speed run. Instead, a heuristic algorithm can be used. Although such an approach does not guarantee a perfect solution, it can prove very effective for solving simple puzzle games.

https://en.wikipedia.org/wiki/Tool-assisted_speedrun#Method