Multi-slice methods allow us to approximate the 3D phenomena without carrying out a full 3D analysis, e. g. in skewed radial flux electrical machines. The idea is to divide a 3D machine into several 2D FEM models, only connected by electrical circuits. Here we show how the multi-slice method is perfect for parallel computation; the computation efficiency is close to that of 2D models in modern parallel hardware. The results are shown to match with 3D computation and experimental results.