Now includes LOD animation (set ranges under View->Adjust LOD ranges).
Did you check that these actually improve the matter? I've encountered quite a few cases in FG where LOD and range animations made stuff worse.
For instance, a bare *.ac model is usually much faster to load and render than a model with *.xml wrapper. Any animation based on a distance usually means you ask for a hell lot of distance computations every frame, and while they're not exactly expensive, more than 1000 of them at some point are. Eventually it may be cheapter to push everything to the GPU and simply render it, rather than pre-selecting on the CPU, because...
...our model shaders are usually set up in such a way as to do most work in the fragment shader, i.e. the cost to render a model is proportional to the number of screen pixels it covers, which is in its very design something akin to a LOD system - as you fly away and the model shrinks to a few pixels, the rendering load becomes marginal.
It would depend on the GPU, but a modern GPU is much better at dealing with lots of models than a CPU is with calculating ranges.