Low FPS in the project, Lod does not help at all

Good day! When you create a scene faced with the same problem (engine Version 4.20.3), with the full Assembly of the building frame rate drops to 15 fps if the building falls completely within the boundaries of the camera, if you approach, it rises to about 37 fpsif to move away, fps drops to 13 , despite the fact that there is a Lod for all the building elements, when the distance disappear all doors of the apartment , in general, all that is inside disappears, replaced by a transparent Plane that will stay visible only some external objects, it seems that the Lod is not working at all,they are visually triggered, reduced detail, but the fps does not rise at all, please help if anyone knows what’s the problem? Computer configurations: GTX 1050Ti, 8GB DDR3 1333 Mhz, Core 2 Quad 9550