...our pathfinder chooses the most TU efficient route...
Actually, the problem could be that the pathfinder (and the actual walking) seems to ignore the costs associated with turning.
The auto-walk down the ramp screenshot by Snickerdoodle has a cost of 20 TUs. If you really must face straight backwards, you need to add one more point for turning 45 degrees and it comes to 21 TUs.
If you follow the same auto-path without turning manually but by taking the steps one at a time (four stops), the result is the same. 20+1 TUs.
If you follow the same path, but turn manually at every stop by right clicking, the total cost comes up to 24 (four steps and four turns).
Now here's the interesting part: If you manually come down the ramp one step at a time, straight down, the total cost is the same: 24TUs.
So, if walking did not ignore the 1 point cost of those 3 turns, the roundabout path and the straight path would have exactly the same TU costs.
Edit: Apparently this is by design. Vanilla legacy?
https://github.com/SupSuper/OpenXcom/blob/master/src/Battlescape/UnitWalkBState.cpp#L330Still, I'm not sure how I feel about this. On one hand, it makes sense that creeping forward cautiously as opposed to charging headlong takes a longer time. On the other hand, it feels strange that we are allowed free actions for leaving the running to the pathfinder.
Ultimately, I'm annoyed that my soldiers seem to be doing strange chicken dances around obstacles and end up facing wrong directions, but I could always imagine them vaulting down the ramp and rolling sideways to dodge the incoming barrage of red hot plasma
.
I hope we are not starting a TU holy war here.