WordPress should behave the same, only dependent on your server resources. I hope you have a dedicated server because if not then you will experience severe outages and possibly cancellation of your hosting service.
WordPress is merely databases and PHP, so amount of files will not affect its use. It is stable. You could have a billion or trillion or quadrillion of everything, it wouldn’t matter, as long as you have the server resources to suffice.
p.s. where are you getting all this?