has there been any testing as to the performance of washboxes/can you tell off the top of your head how performant they might be? i took a look at the scripting but couldn't get a great idea from that.

i did my best to make it as performant as i could within the constraints of the api, personally im satisfied with how it behaves, and honestly i tend to avoid writing bad performance mods like the plague.

can you give a rundown of the logic so i can get a grasp on what all it's doing?

so basically it counts how many pumps are connected to the input side of the washbox, and instead of iterating all fluid connections to figure out the members of a fluidbox it instead checks the other way around by just checking which fluid network id each pump is on.

inside the washbox there are linked connections that decouple during this check so that the output side of the washbox does not get considered.

fascinating. i assume this is cached or batched or some such?

they're batched yes.