Half a million polygons is not too bad! It's actually far enough to build amazing 3D games. If you want to see a live application, here you have the 3D data visualization globe demo compiled for the iPad/iPhone:
The application loads 35 000 geo-localized hot spots and uses Minko's streams API to create the corresponding 3D geometry dynamically. You can find the code on Aerys' GitHub. A beta for Minko 2 should be available this week on GitHub. Stay tuned!