Mecanim Game Objects Optimizer

If I've understood correctly, Game Object Optimization builds its own rig based on the layout of an imported rig, the imported rig never ends up in the compiled game. So does this mean that we don't have to worry about extra bones like control bones etc. as they'll be removed by Unity?
The Rigify rig from Blender for example notoriously adds an extortionate number of bones which could be worrying performance-wise. Does Unity completely take care of this?