Improve 3dtiles FPS

hey everyone
I am currently using c++ to make a tool to convert obj to 3dtiles. It’s time to optimize tileset.json to improve performance. But at the moment I don’t know what to do.
Currently, I create tileset.json by using an octree to increase the number of models layer by layer. But I don’t know how to calculate the geometricError of each layer, how to calculate the geometricError of each b3dm in cesium to show and hide the model, please give me some suggestions.
When loading 3ditiles in cesium, the rendering statistics of b3dm converted from the same model using different tools are different. When the “commands” is very low, FPS can provide. How to reduce the “commands” in “rendering statistics”. Please also give me some suggestions。