Right after it was launched, the iPad Air was tested and showed that it can be up to 80% faster than the fourth generation model or 5 times faster than the iPad 2!
Taking these data into account, we soon imagine that the Second generation iPad mini would follow the same path. And as the first generation iPad mini has the same internal components as the iPad 2, the trend was that the new 7.9-inch tablet with Retina display was 5 times faster than its predecessor.
But not quite. As we can see in the test (benchmark) performed with the Geekbench tool, most likely due to the smaller battery than the iPad Air, Apple chose to reduce the clock the second generation iPad mini A7 processor, leaving it at 1.29GHz (pretty much the same as the iPhone 5s, which runs at 1.30Ghz). Comparatively, the iPad Air's A7 runs at 1.39GHz.
I venture to say that few people are able to notice this difference in practice, the gains should be even 4-5 times greater, but it is interesting to see how far the company goes to make things more balanced between performance and energy efficiency.