The Titanic was never built for speed, but for size and luxury, and both Ismay and Smith knew this. Smith was not steaming reckless and full-speed to New York to beat the Olympic, 2 of the 29 boilers weren't lit.They conversation between Ismay and Smith is very telling in the reception because of the way Ismay is speaking: "Well, we did better today than we did yesterday. We will beat the Olympic and get in to New York on Tuesday night." The first sentence is the most important because to me the way Ismay is talking ensures that he is part of a project or a work in progress with the objective of getting to New York a day early. That is why he is being told this information by Smith, because he is influencing the speed. If he wasn't Smith would have no reason to tell Ismay anything.
Captains are always under pressure, their ships HAVE to arrive on schedule at the destination. The only reason I see to speed up was to deal with a delay of an hour caused in Southampton (the New York incident). Titanic speeded up to 22,5 kn, with that speed she would arrive in New York right on schedule.