This paper describes the R&D status of eRTI 1.3, the implementation of the principal functions of the High Level Architecture Run Time Infrastructure (HLA-RTI) interface specification 1.3 (IEEE 1516.1P) and its applicability to large scale distributed cooperative processing systems (DCOPS). In order to achieve flexibility and expandability for supporting DCOPS, standardized system architecture and interface to interconnect heterogeneous systems are mandatory. While the HLA is designed for providing the way to satisfy the above objective particularly for distributed simulation systems (DSS), its architecture and methodology are quite useful also for DCOPS. We propose a DCOPS/HLA system architecture which utilizes HLA as a communication infrastructure for DCOPS. The system architecture of DCOPS and DSS are very similar from the RTI software design viewpoint. If we can show that the functions provided by the HLA are sufficient, and that the performance of infrastructure software is practical, HLA can be applied to DCOPS. We focus on performance issues. We first give an overview of the DCOPS/HLA architecture and our latest version of eRTI 1.3, then show the results of performance evaluation compared with the DMSO's (Defense Modeling and Simulation Office) RTI. The results indicate the upper bound of the communication frequency among agents and subsystems when DCOPS is implemented on the HLA.