LOD would have very little impact if you have 500+ visible models. I've done benchmarking experiments and found that, for 1000 visible entities, the frame rate is unbearable, even if just 3 vertices, 1 triangle each. What you need to do is combine your models so that they are between 2000 and 5000 polygons each for the best performance and greatest detail. In theory, my city world, of which has nearly 2400 buildings, could still render faster than 100 fps and I wasn't using LOD (but rather over 20,000 polygons and vertices - a bad thing to be doing).



This logarithmic graph tells how the frame rate is for the number of polygons against the rendering rate.