© 2017 IEEE. Performance-based quality evaluation of database conceptual schemas is an important aspect of database design process. Performance of user applications strongly depends on the logical and physical database structures derived from the conceptual schemas. This work presents a complete process of performance-based quality evaluation of conceptual schemas. It shows how to express a conceptual database schema in a notation of simplified UML classes. It proposes a new specification of object algebra for representation of conceptual level database applications. Transformation of conceptual schemas and expression of object algebra into implementation schema described in the paper allows for precise estimation of the processing costs of database applications and for precise evaluation of performance-based quality of conceptual schemas. An experiment conducted as a proof of concept for the performance-based quality evaluation procedure concludes the paper.