More Meshes cause less FPS or the opposite?
When I started to render OpenStreetMap in 3D, each building and tree was an extra Mesh. Great for selecting. But to show all buildings of a city to the horizon was impossible. To get more FPS I merged the Meshes to small tiles of about 400x400 Meters. Then I added shadows, reflecting water etc. and the FPS are down to 2-4 again. The only way to get back to 10 was to define the horizons less far away which looks odd.
Desperate, I gambled with the tile size. Bigger tiles: less Meshes better FPS? NO! Thinned tiles with more Meshes caused more FPS! Now I am worried. Why? About 100x100 seems to be the optimum. Can anyone explain this?
(Ok, there are things like self casting shadow that makes the tiles CPU heavy.)