I could see a priest, in some cases, offer Mass quickly ... for the benefit of the faithful. Let's say you have an early morning Mass and people need to be at work soon afterwards. Priests are taught that the Mass is not their own persona prayer time, but the public prayer of the Church, and also offered for the benefit of the faithful (except at private Masses). Now, with that said, you can't give the impression of being irreverent and sloppy ... for the same reason, that it's the public prayer of the Church. So a balance must be found between length and reverence. If I'm a priest, I can't just go off and decide to mediate for 15 minutes during the middle of the Canon right before the consecration or something (yes, I know, some saints were drawn into ecstatic states, but those are special cases) ... making people late for work or else forcing parents to deal with antsy toddlers for an extended period of time.
As a priest, I might WANT to take my time and read the entire Mass slowly while meditating on each phrase, but I make the sacrifice of not doing my own will but instead doing what's in the best interests of the faithful.