A computer implemented method and system for optimizing thermal performance of a computer system. An identification of a set of processor cores associated with the computer system is made and a thermal index is requested for each of the set of processor cores to form a set of thermal indexes. Proximity information and conductive property information associated with the set of processors is loaded and software is mapped to execute on an optimal processor core form the set of processor cores based the set of thermal indexes, proximity information, and conductive property information.