Only one add-on installed, UTX Europe 2.1 that is, no newer versions available at scenerey solutions
Yer ask and yer shall receive, here is more zoomed-in screenshot. i have markes some spots that may show why i think the minor rural roads are the problem here:
http://postimg.org/image/d07ndzsjn/
Did that!
Vanilla FSX and vanilla p3d look exactly the same btw.
Installed FSX and UTX 1.4 for comparison, thats how it should look like in p3d!:
http://postimg.org/image/tytjlh3kt/
So i guess the conclusion is right that an imcompatibility between utx an p3d is the problem here. but im a bit surprised that i can't find any reference to this problem in the whole internet because i thought there were many p3d+utx users now.
so i think there is a problem, of what kind i have to figure out, exclusively on my end :/