With all the speed of a rusty iron door, Cinderella turned to face the concerned voice...

It's not entirely fair to claim that rusty iron doors are slow. They have no say in how slowly they're opened, and it's up to whoever's applying the force to decide that. It is nonetheless a reasonable expectation that they will be opened slowly, but the point is simply that it is not the door itself at fault.

Someone first allowed it to rust, and then someone opened it slowly. We can go even further back with the blame, pointing fingers at whoever had the bright idea to build an iron door in the first place. Did they even once consider the weight of such a thing, or the humidity levels of the area around it?

No, this door bears not one bit of responsibility for its lack of speed.