Nice to see Maploader being mentioned here.
As someone who’s dealing with mapping very often, I see the biggest, potential issues here.
A) ymap conflicts, destroying the original parental structure
B) unoptimized maps
C) too many maps in one place, overloading the memory, causing more detailed LODs not to load in
Now, from my experience of building a new city, you can have LODs, optimized drawing distance and occlusion to boost fps, BUT if you have simply too many information loaded in about objects in the nearest vicinity (ytyps), this can result in memory not loading anything else in. Just because your GPU doesn’t visualize it doesn’t mean it’s not bloating the memory. This is very poorly and theoretically explained, but it’s something I noticed recently.
The “easiest” solution would be to lower drawing distance, but for entire ymap. Leaving more breathing room for the client. Presuming you have no ymap conflicts.