Depends what's inside model, if it's just a bunch of pointers to meshes, materials, etc. that are allocated and owned elsewhere then it's really not a big deal or concern.
What is "a bunch of" nowadays? My knowledge about efficient programming is still at the level of 20 years ago :) Looking at the DrawModel function, it looks like it's passing around 400 bytes of data structures for a model with one mesh (assuming that matrix operations are inlined).
