This morning I've done my own investigation on the route I've been experiencing the issues the most.
1) I removed all the passengers from the trains and stations (since N3V blames us for using not optimized content, but they created quite heavy passenger assets by the way).
In this case nothing changed.
2) I created session with NO AI trains. And guess what? It's shuddering much less and the objects stopped blinking - they reveal completely with no issues.
It makes me conclude that AI trains take to much resources of the game.
I've sent it to N3V support.
1) I removed all the passengers from the trains and stations (since N3V blames us for using not optimized content, but they created quite heavy passenger assets by the way).
In this case nothing changed.
2) I created session with NO AI trains. And guess what? It's shuddering much less and the objects stopped blinking - they reveal completely with no issues.
It makes me conclude that AI trains take to much resources of the game.
I've sent it to N3V support.