I’ve drawn a model up and created different scenes for each view point. I’ve noticed that some of the lines are thick black namely my steel beams and walls. I’ve checked and they’re a solid group. I’ve even tried to do a cleanup on them. I don’t understand why they are different that other lines- all my lines are connecting
I’m not seeing the same scenes in your model as you are showing in your screenshots. For some of the scenes you have Section Line weight set to 3. You could reduce that.
Profiles can affect the performance of sketchup if your file gets bigger, there’s no need to have them activated if you don’t have rounded or smooth faces that you need to be visible.