I think you could call it a play about consumption, or at least consider that one of the themes.
Salieri is consumed with destroying Mozart. He is jealous of Mozart's ability as a child prodigy and watches Mozart grow as a flamboyant, immature, but extremely talented musician. Mozart's ability to court a lady that is one of Salieri's students only further fans the flame of his envy of Mozart.
Mozart on the other hand, is consumed with having a good time. Even though he will work extremely hard, he drinks merrily, plays hard, dresses vainly, and socializes to the extreme. He also has a great desire to please his father even after his father is long gone. Mozart died at the age of 35 and the way the play is written suggests that his lifestyle which was of great financial and health expenditure helped lead to that death.