ipad mini 4
From left, an iPad Mini 4, an iPad Air 2, and an iPad Pro. Stephen Lam/ Getty Images

The iPad Mini 4 was introduced by Apple last Thursday to great promise. "We've taken the power and performance of iPad Air 2, and built it into an even smaller, mini enclosure," said Apple marketing Senior Vice President Phil Schiller. But new research from Ars Technica shows that's not entirely true.

Press documents confirmed the Mini 4 would use an A8 chip instead of an A8X chip as used in the Air 2, but until now it was unclear what difference it would make. It has now been confirmed that the chip inside the Mini 4 runs at 1.5GHz, faster than the 1.4GHz A8 chip inside the iPhone 6 and hitting the same clock speed as the Air 2. The chip is left in the dust by the Air 2, however. This is mainly because the older tablet has three CPU cores instead of two.

Ars Technica used the Geekbench benchmarking tool to compare the devices, which produces a higher score the faster the device. It found that the iPad Mini 4 scored 3,121 on overall multicore performance, far behind the Air 2, which scored 4,542 on the same metric. But even on single core performance, the Mini 4 scored 1,716, compared to the Air 2's score of 1,831. Whether on single core or multi core performance, the Air 2 has the upper hand.

The difference is likely to go unnoticed by casual Web browsers and movie players, but design professionals or graphics-intensive gamers may want to opt for the Air 2 to make sure they're getting peak performance. However, for the best money can buy, it may be worth holding out for the iPad Pro, which comes with an A9X chip. Apple says that one has double the graphics power of the A8X.