Barring mechanical problems, any road bike with drops and slick tires will be just about as fast as any other, from a commuter's point of view. Of course ridden by the same guy the $2000 one may get there a minute quicker---to a racer that's huge, but to a commuter it's only the amount of time it takes to wait for a light to change. As a commuter, the way you will really save time is (1) by planning an efficient route (2) by having reliable components, solid wheels that stay true and good flat resistant tires, and maintaining your bike regularly to avoid breakdowns and inefficiency; and (3) by upgrading your engine .