This thesis will try to explore the concept of co-simulation and some of the most popular framework that are available. Another point of discussion will be the analysis of different parallelization techniques that had been implemented inside each environment in order to scale up the size of a simulation. The focus is on the performance and on the technique to create and design efficient simulators to integrate inside co-simulation environment to allow real time systems to interact with digital simulation. The aim of this thesis is to produce an analysis of the performances of different co-simulation frameworks and in particular provide benchmarks about parallel implementation for simulators, evaluating not only time related data but also analysis on usage of resources.