Today’s calculations can get a little intense if you treat every numeric range as equally important. There can be a long distance between changes in the input->output relationship.
I found an interesting video from a while ago in which CFD people talk about a similar issue in deciding where to allocate computational resources in the simulation of a Mach cone, where the vast majority of the simulation is plain air with nothing interesting happening, but there is just a very small boundary in which super-interesting things are happening.
My solution for part 2 ran in 2ms and I didn’t do anything too interesting to achieve that. While this topic is interesting, I’m not sure Day 5 was a good candidate for this approach.