TAILSIT is a company based in Styria, Austria, that produces custom-fit simulation software tools for electromagnetic problems and structural analysis. During this SHAPE project TAILSIT’s electromagnetic simulation software has been ported to HPC machines with the support from an expert from the VSC Research Center at TU Wien and using the computing resources of the Vienna Scientific Cluster (VSC, https://vsc.ac.at). A careful performance analysis revealed several bottlenecks and limitations that were addressed by implementing optimised communication strategies with the Message Passing Interface (MPI). While the previous version of TAILSIT’s software simulation tools relying on shared-memory parallelism was restricted to typically less than one million surface degrees of freedom, the new and optimised version employing distributed-memory parallelisation with MPI allows to treat problems up to 50 x 10^9 surface degrees of freedom. In addition, access to the HPC resources allowed to test and further optimise the shared-memory version of the fast multipole method FMM library.