Check to see the starting key and time signature in the piece. Scan ahead to see if there are any changes in either during the course of the piece. If not, you need only read the notes, and can avoid having to speed up or change key.
Learn to read groups of notes as blocks. Although this will only come with practice, you will soon learn to read four notes as a particular scale, which will quadruple your note-reading speed. Practice with pieces you are unfamiliar with, in order to improve your reactions.
Practice new pieces every day in order to improve your ability to react and interpret notes. You will soon be able not only to improve your note-reading ability, but you will also learn to anticipate notes which will follow.
Practice regularly. Reading notes whilst playing is a skill which can be lost, as well as nurtured. Simply put, the more you practice, the faster you will improve. Although there are no shortcuts, regular practice will enable you to show a marked improvement, which will spur you on.