For a given system, some experimentation may be needed to determine the best number of threads to use. In many cases, using half of the available hardware concurrency works well. This comes as a result of there often being two cores per memory port on many modern processors. In other words, for many problems, the FDTD solver cannot load and store data from CPU memory quickly enough to use all available threads or hardware concurrency. The extra threads are idling waiting for data, and a performance hit is incurred due to increased thread context switching.
Also[[EM.Cube]] will attempt use a version of the FDTD engine optimized for use with Intel's AVX instruction set, which provides a significant performance boost. If AVX is unavailable, a less optimal version of the engine will be used.
After the sources, observables, and mesh are set up, the simulation is ready to be run.