I know that this has been talked about before but I've read a few different explanations (and possible cures), so I was just wondering what the latest thinking is. I also want to clarify my own undestanding of the issue.
It's only become an issue for me since I started improving the terrain heightmap in certain areas. It's never a problem where I start from. It only appears after I've flown a few miles from my starting point. If I then restart at that point the problem goes away. Cultivation may be either floating or buried, and the effect seems to be greatest where the discrepancy between the default and high res terrain meshes is greatest (ie steep slopes, valleys etc). Oddly enough I've never noticed it happening with trees - only buildings.
The first thing I thought to blame was my Ordnance Survey cultivation, which is based on 100 x 100 km areas and often involves TOC files well over 1 GB in size. So I decided to split the cultivation into 0.2 x 0.2 degree areas (roughly 20 x 20 km - a bit less than a level 10 square). Unfortunately, however, this has done nothing to improve the situation.
My understanding is that it occurs because the buildings load before the higher res mesh, so they are placed on the lower res mesh. Is that correct? If so, it means that either the buildings need to load more slowly, or the mesh more quickly? Any thoughts would be greatly appreciated.