I am not aware of a plugin that can analyze and break down model size and complexity.
You currently can:
- open Window → Model Info → Statistics to see the number of components
- open the Components Browser to list all components
- use 3D Warehouse to filter components (that are in 3D Warehouse) by polygon count and file size
- export all components as skp file and sort them by size
It would indeed be a cool idea to have a profiler plugin that can analyze skp files. For components, it could calculate the polygon count. However it is not possible to get the file size of a component without exporting it (one could compute an estimation metric considering empty model file size, number of entities of that component, number and size of materials used by that component etc.)
Something like this: