The design of class models for information systems, databases or programming is a delicate process in which experts of the domain and designers have to identify and agree on the domain concepts. Formal Concept Analysis (FCA) has been proposed for supporting this collaborative work and fostering the emergence of higher level entities and the factorization of descriptions and behaviors. More recently, an extension of FCA, Relational Concept Analysis (RCA), has been designed to extend the scope of FCA to the emergence of higher level domain associations. FCA and RCA build a kind of normal form for models, in which the factorization is exhaustive, and the specialization order is adequate. The counterpart of these strong properties is a worst-case exponential theoretical complexity. In this paper, we study a practical application of RCA on several versions of a real class model in order to give precise figures about RCA and to detect which configurations are tractable.