Its not really a bug,but it affect preformances on older PCs.
I know it makes switching from Bl1 to bl(X) faster but why its rendered when you can't access it or drive on it. Making it only render on respective configuration should work.
Video :



And if you dont beleve me about preformance,I get way lower fps facing that area on track (industrual) then when on opposite side. (Yea,Im using pc from 2007,lol)

Occlusion and frustrum culling are there to ensure that any object (props, buildings and roads) that you can't see won't be drawn. And it works quite well in LFS (even a bit too agressive sometimes), so you don't have to worry for that, it's normal to still it when you are in SHIFT+U mode.

Disabling the industrial area when you look on its direction in non open configurations would make the environnement look different and less detailed in the background than it should be, so I don't think it's a real solution.
If you don't have detail distance set to lowest, you should maybe try this.

Isn't it like this for all tracks? Anyways, I quite like this as it makes wall-glitching pretty fun

Quote from nacim :

Disabling the industrial area when you look on its direction in non open configurations would make the environnement look different and less detailed in the background than it should be

They can put placeholders instead of full detailed map,Im sure whole map is rendered and it doesnt matter where are you on map. And you say it will look diffrend and less detailed,whats up with rest of maps?

Quote from neonmateo :

They can put placeholders instead of full detailed map,Im sure whole map is rendered and it doesnt matter where are you on map. And you say it will look diffrend and less detailed,whats up with rest of maps?

There are already LODs to reduce the poly count of distant objects, but obviously when you get close enough it will load the fully detailed model.

For now, developers only updated Westhill and Blackwood, and released Rockingham, which are much more detailed than the others. Their goal is to update every track with this new quality standard, so I won't expect performance improvements on theses area (actually, object culling has been updated when Westhill was released to get back some performance).

I don't know the specs of your PC, but you should maybe consider upgrading your GPU to at least something like a used HD 7850, or ideally a new AMD RX 560 2GB (they are both overkill for LFS (at least for now), but at least you'll be able to play other games, as long as your CPU can handle them).

Quote from nacim :

...I don't know the specs of your PC, but you should maybe consider upgrading your GPU...

I didn't say anything in specific. Yes,my pc is bad but developers should update system requirements for the game to suit new tracks.