Computer simulation techniques are widely used in various fields to design and verify the functionality, performance, quality, or safety of a product. In electrical systems, with increasing operational frequencies, capacitive and inductive couplings between parts in an embedded system might have to be taken into account. Therefore, traditional circuit analysis are not sufficient for such problems. Hence, other simulation approaches such as Partial Element Equivalent Circuit (PEEC), Method of Moments, and Finite Element Methods, and other have been developed to fulfill this need. By using the PEEC method, the simulation of the functionality of an electrical device can be combined with an electromagnetic analysis. Thus, the method has been widely used in combined circuit and electromagnetic modeling on problems in different classes in power electronic industry and antenna design. The main aim of this paper is to demonstrate how multi-core systems can contribute to improve the performance of a PEEC-based electromagnetic simulation tool and to show that the improvements make it possible to solve larger and more complex problems in a reasonable time.A PEEC-based solver has been developed at Luleå University of Technology. The kernel of the solver has been implemented in C++ and is designed to run on different desktop platforms and operating systems. It is known that in the PEEC formulations there are large, dense, and in many cases non-symmetric matrices which increase the computational costs. Hence, using an efficient and robust library as well as support for the recently advanced hardware, is vital and will highly affect the performance of the solver.