All boats at slower speeds are considered displacement boats, which means that they are displacing, or pushing, a wave of water out of their way as they move. Maximum hull speed of any displacement boat is determined by the length of the wave that they are pushing, which is determined by the length of the boat's waterline. At the maximum displacement speed the boat is sitting in the trough of this wave. There needs to be quite a bit of power to get a boat up over the crest and out of the trough to break through and plane on top of the water. Once planing, even the shortest of boats can be extremely fast.
Weight is one of the biggest factors to determine a small boat's performance.
A light boat is generally a fast and responsive boat. Light weight also means less lateral area in the water which generally means more maneuverability. The drawback to having a light boat is that it usually means a less stable boat. Length is a capacity and speed determinant of most designs. Longer boats generally have more buoyancy, translating to more capacity.