Traditional cost estimation models in software engineering are based on the concept of productivity defined as the ratio of output to input; for instance, detailed software estimation models, such as COCOMO, can take multiple factors into account, but their multipliers lead to a single perspective based on the productivity concept. A less explored relationship in software engineering is the one between productivity and performance. This paper presents some classic concepts on the multidimensionality of performance, and proposes some suggestions to implement multidimensional performance models in software engineering based on certain fundamental concepts from geometry, that is, the QEST/LIME family of models.