Efficiency drop in large BR housings ???

Hello everyone, I would have a little question, and that is a software for calculating the housing volume. And if I calculate a very large box (larger than the system as optimal) to get out even more low bass, the level drops around some db. Could there be other disadvantages with large bass reflex boxes, such as dynamics, impulse fidelity?? Would I be happy if someone took some time and gave me some answers. Thanks jellyfish