iGO Primo: Route calculation algorithms/formulas

[GPSveteran]

Can anyone point me at the right direction for this?

As I recall there are algorithms/formulas "somewhere" inside iGO that are calculating the Fast or Short or Easy etc. routes for a destination.
I remember years ago that it was possible to alterate these formulas. There where something like 70%X+15%Y+10%Z ...I don't remember exactly...but you could change the gravitas of each type of road during the calculation of a type of route.

What is my problem exactly.
For the last year or so the maps (TT at least, maybe Here too) of my Region seem to have under the hood "changes" (not visible in the terms of road names etc.) that make the same route to be calculated differently.

For example:
You want to go from A to B. GREEN was the preferable "fast" route with the "old" 2017+ maps.
With the 3-4 latest maps iGO Primo chooses (and insists!) for the RED route, even if you force it to keep rerouting following for the first half of the green. Similar results if you choose "Easy".



Obviously I cannot change the compiled maps, so my thinking is to adjust these "algorithms" inside the program OR maybe the speeds of the large national roads. (Are they somewhere inside the profile folder? I forgot.)