Indoor lags (Fallout 4)

I play on average settings, only the anti-aliasing is maximum. In the wastelands, 40-60 fps, in buildings, in principle, also in the region of 60, but not in all. For example, in the room where you need to find the subway, 20-25 fps starts immediately from the entrance, if you go deep into the building again all 60. I would understand everything if it was the other way around - in an open area or at a height from where you can see the floor of the map, but so that the friezes are in rooms where there is nothing ordinary even from textures and lighting ... this is at least strange. I read that many people have this problem, even on powerful machines. What could be the problem? Maybe someone somehow solved this, or at least established the cause of the lags? Or, as usual, we are waiting for patches from the gazebo?