The paper presents a performance model that can be used to optimally distribute computations over heterogeneous computers. This model is application-centric representing the speed of each computer by a function of the problem size. This way it takes into account the processor heterogeneity, the heterogeneity of memory structure, and the memory limitations at each level of memory hierarchy. A problem of optimal partitioning of an n -element set over p heterogeneous processors using this performance model is formulated, and its efficient solution of the complexity O( p ³ × log ₂ n ) is given.