Runtime vs. particle count N for a 128³ grid with the Python code on an Intel Core i7-9750H. The time spend on the FFTs (blue) is roughly constant, and the time for the evaluation of the particle accelerations and/or densities grows linear with N (orange, red, and purple). The total runtime shows a crossover around 10³ particles (black). The dashed lines are guides with slopes of zero and one.