The documentation states that this is going to change in the future, but as of now, each Line Art modifier calculates the occlusion of the scene independently so multiple Line Art Modifiers are horrible performance-wise. I have a decent machine, and I have to make sure I have only one of them in the view layer at once, or else Blender runs so slowly that I can't actually use it. And the way Line Art works you really do need multiple modifiers to compose a scene, because you don't have many options in determining where strokes are placed within each individual modifier.
So, I'm not expecting much, but has anyone found a setting or workflow to limit the slowdown from Line Modifiers that's less clunky than my current strategy of only showing one modifier at a time until I render? I keep getting tempted to going back to my Freestyle set-ups until the devs sort this one out.