Ideally there would be a full scene memory report available from corona like the texture memory useage csv, but for materials and geometry.
Thats a good idea.
In the mean time I suppose the only thing I can think of is the old 50/50 way (remove 50%, hit render), do it again until the speed jumps up significantly, then you know which chunk to investigate.
Another idea which could give you more info (for geometry, and other info too), export one of those chunks as fbx (ascii not binary), then open the fbx with notepad. This will give you a tonne of info about the objects and its data but you would probably need a custom parser to get the data you want sufficiently, unless you dont mind scrolling though millions float values lol.
