Neumann’s Computer and The Brain book is way out of date in terms of today’s hardware, but funnily it is still relevant in this metric. Biological systems are more analogous to a distributed system of small, very slow CPUs. Even GPUs that somewhat close the gap in-between the few, crazy fast CPUs vs the aforementioned many, slow ones - are still much faster than any one neuron in calculations, but are still overly serial. It is not the number of CPUs, but the number of their connections that make biological systems so powerful.