I build my tracks very basically at first, a road, enough terrain and walls for guidance, then I export and ride the track to see if all is OK. After that I work at getting the track fun to ride on and test it with a few cars for drivability.
That done I start to put more walls and fences on. I've notice that once fences are placed, the whole export thing slows down. In fact, sometimes the BTB stops responding. I also find it better to use the strips with people on them are better than individual models. The more models, the slower the export and load.
As we learned in Engineering design. K.I.S.S. Keep It Simple and Straight forward.
no K.I.S.S stands for keep it simple stupid . we started with the base got the track working right, now where filling the track out and the export times have exploded . it doesn't matter i was just curious if someone else has encounted similar , and keeping it simple maby good for some but were looking for a complete immersion, our tracks been tested by actual drivers who race on the track and they've agreed its spot on