The present invention relates to controlled release compositions that include: (a) a slow release component, comprising one or more performance additives in the form of a solid or semi-solid mass; and (b) a fast release component comprising (i) a matrix material and (ii) one or more additives that can be dissolved and/or dispersed into the matrix material as well as additive delivery systems and processes using such compositions, and which release one or more additives into a fluid.