Modular space systems are an innovative and future-oriented concept, offering the flexibility to adapt to diverse mission requirements. In our previous paper, we introduced the Twins4Space project, a modular and flexible architecture utilizing a SpaceWire network to connect distributed nodes. In this paper, we focus on the empirical performance evaluation of the system, presenting detailed measurements of its communication layer. Key performance indicators such as SpaceWire Time-Code latency and network data rates are assessed, which are essential for maintaining predictable operational conditions within decentralized nodes. Our findings demonstrate that Twins4Space can effectively meet the rigorous demands of future space applications, providing robust communication and swift reconfiguration capabilities. Furthermore, areas with optimization potential are identified, offering opportunities for further performance improvements. This validation underscores the practical potential of the Twins4Space approach in enhancing the efficiency and reliability of space mission infrastructure.