To compare with desktop CPU, my Macbook has a Core i7 running at 2.3 Ghz, with 4 cores (8 threads with hyper threading), and stockfish runs at around 5.3 M Nps. As it has 4 times more threads than the iPad Mini 2; you can see that both CPUs are about as powerful per core, despite the A7 runs at half the speed of the Core i7. This is VERY impressive !