This paper presents the A-Diakoptics methodology (Diakoptics based on actors) for the high performance simulation of microgrids. Microgrids are clusters of loads and microsources that operate within a single controllable system, which provides electricity and heat to its local area even if they get separated from the distribution system. Several commercial solutions are addressing this topic using numerous methods; however, to keep the computing time required to solve the system when the size of the system grows represents a major challenge. In this paper, this challenge is addressed by separating the distribution grid in independent subnetworks. Then, for the computational implementation, each subnetwork is assigned to an independent solver using the actor model. As a result, the solution algorithm is composed of multiple parallel and concurrent solvers. These exchange information using high-speed communication interfaces for reducing the computational burden without losing accuracy. A-Diakoptics is an advanced algorithm that combines existing methods for simulating large distribution systems; these methods are upgraded to make them suitable for parallel processing and to cover the basic needs for the simulation of smart grid applications.