An apparatus for applying EM energy to a load may include at least one processor configured to receive information indicative of dissipated energy for each of a plurality of modulation space elements and group a number of the plurality of modulations space elements into at least two subsets based on the information received indicative of dissipated energy. The processor may also be configured to associate a power delivery protocol with each of the at least two subsets wherein the power delivery protocol differs between subsets and regulate energy applied to the load in accordance with each power delivery protocol.