After the training phase, is it better to run neural networks on a GPU or CPU?
Running trained artificial neural network is repeated performing of a matrix with vector multiplication and performing the same nonlinear function for each element of a vector. If both operations could be parallelised and vectorised, it is what is GPU well suited for. But it strongly depends on the size of given vectors and matrixes which depend on the size of the neural network. For small nets, CPU could be faster than GPU but it would not matter anyway. For huge nets, GPU would be probably much better suited if algorithm is written right.