Thanks for reply!
Im not really sure too 
I have 0 SM on scene, only BP for sky, 0 loaded cells from world partition and 5 long splines (they’re still visible). When my camera spots splines on the screen, my fps goes dramatically low but when i press “G” and hide splines, everything is ok. I’m sending two pictures. The first one shows a spline, fps 30-35. As you can see, the terrain is not loaded and the spline is still visible. On the second I hid the tools and the grid and fps increased to 70+.
