Software quality can be described by maintainability, usability, security and performance properties. Performance is generally considered a critical requirement in systems such as distributed systems based on the Web and real time embedded systems. However, the software development processes do not provide suitable support for the construction of a software system that needs to meet performance requirements. RUP (Rational Unified Process) is a well known software engineering process that provides a disciplined approach to assigning tasks and responsibilities within an organized development; however, it has little support for meeting performance requirements. The objective of this work is to propose a more disciplined approach for the extension to RUP for the development of systems to address performance. The performance is embodied in RUP as a knowledge area (discipline) with activities and roles defined through SPE (Software Performance Engineering) and according to the architecture of process engineering UMA (Unified Method Architecture).