How does the mod impact UPS? I assume it is only active on the tick a train leaves a station, but how expensive is each calculation? Is it noticeable in any way?

Time Usage puts it around 0.003 seconds on my megabase, which runs ~80 trains all the time. It's extremely negligible.

Hrm. I'm starting to worry about UPS. See the following where ATP is the top mod in the time view (1.247/0.017/19.659). I have an unspecified large number of trains, you can see the trainstations in the map view. Unfortunately I couldn't find a quick console command to count trains.

https://i.imgur.com/RVsZUtO.jpg

https://i.imgur.com/WTdg5rr.png

Found our totals:

1201 train stops. 632 trains. 92630 (184 km?) rails

FYI our base is "idle" at the moment in the lull between circuits and science packs while we expand to create the next level.

Reading in the code a bit, iterating over every item and merging tables, you might have an opportunity to make a shortcut like "color by first item".

Unfortunately we had to disable ATP yesterday due to our hitting our UPS cap. It was expensive in UPS, so it was the first mod to go.