The Premium Heart has a power up factor. The strength of the Premium Heart is directly related to how full Tifa's limit bar is. This can be a bad thing at first, as when her bar is empty, the attack power of the Premium Heart is virtually nil.

However, the Premium Heart does gain power very quickly, and about one third of the way up the limit bar, its power will break even(meaning that from there on up, it just keeps getting more and more powerful). One good thing is that this always assures maximum power for Tifa's limit breaks.