In general, I think there is a possibility for higher performance, currently, I am focused on minimal features and critical bugs first (e.g. flicker when animation change, rotation not working for some mixed mesh models.)
Good point
The idea about frames for models also was good.
to be able to make skins
For creating lower poly models in blender, try the second answer here - decimate (FoozleCC pointed me at it.)
I did it, and got 2.5K polygons, it gives 30fps on mobile, but if to add even one more model, fps drops till 15
I learned how to make models better, and i can decrease the polygon count to 1.5k, but still hard to add more than 3 models like this on the scene