Simulation-based design optimization is a key technology in many industrial sectors. Recent developments in software technology have opened a novel range of possibilities in this area. It has now become possible to involve multiple organizations in the simulation of a candidate design, by composing their respective simulation modules on the Internet. Thus, it is possible to deploy an inter-organizational design optimization system, which may be particularly appealing because modern engineering products are assembled out of smaller blocks developed by different organizations. In this paper we explore some of the fundamental performancerelated issues involved in such a novel scenario, by analyzing a variety of options: centralized control vs. distributed control; generation of new candidate designs one at a time or in batches; communication and computation performed serially or with time overlap. Our analysis provides useful insights into the numerous trade-offs involved in the implementation of inter-organizational design optimization.