Recently, an ever increasing number of e-Commerce tools has been made available that are able to help customers by generating purposed recommendations. Many of them are centralized so that they have to face problems related to efficiency and scalability. A few of them are distributed, but in this case, the complexity of the e-Commerce process implies computation overhead on the client side, which is often unsuitable if mobile devices are used by customers. In this paper, we study how the software distribution in recommender systems affects their performances, depending on the characteristics of the e-Commerce population. To this end, we present a distributed testbed architecture for e-Commerce recommender systems using a multi-tiered agent-based approach to generate effective recommendations without requiring such an onerous amount of computation per single client. We use such a testbed to study the main advantages and limitations associated with the problem of distributing the computation of recommendations. the presence of message delays, do not affect the recommendation activity. Indeed, in these cases, a global knowledge about the state of the system is not generally required, and message delay is not a relevant problem because the communication model is of the peer-to-peer (P2P) kind.However, it is not clear to what extent these advantages depend on the characteristics of the e-Commerce community [13] and, more generally speaking, what are the actual limits of the adoption of a distributed approach in a B2C e-Commerce scenario. This paper is meant to provide an answer to this question.In order to understand why such an analysis is important, consider a case where we want to design a recommender system for supporting an e-Commerce community such as, for example, a portal for sellers and customers of antiquarian products. In this case, a possible solution consists in adopting an agent-based system such that a software agent is associated with each seller and each customer to support them by generating recommendations. Notice that, in an e-Commerce scenario, there are many activities to support. To illustrate, customers have to be provided with recommendations about the antiquarian products they will be most probably interested in. Also, they will need suggestions about the most convenient merchants. Moreover, some negotiation activities between customers and merchants might be necessary, as well as a support for the delivery process and for the evaluation service. The question is: from the efficiency viewpoint, is it better either to design a single software agent assisting its user (either a customer or a merchant) in all those different activities, or to provide each user with a set of agents, where each agent is dedicated to a specific activity? In other words, given for granted that various actors are assumed to be associated with different agents (horizontal distribution), it must be decided if having a single agent per actor is more convenient than distributing the activities associated with the single a...