Wow. According to this chart of performance benchmarks, Apple’s A9 ARM processor is 57% faster than its own A8 chip in single-core performance, increasing from a value of 1,605 to 2,522. (Without digging into it I don’t know what the “unit” is in these numbers. I only know that they are Geekbench values.) Single-core performance is usually the important metric for most applications, and that’s a huge gain.
I bought an HTC/Google Nexus 9 back in January — which is pretty speedy these days thanks to Android 5.1.x — and the new A9 chip is 29% faster than the Nexus 9 in single-core performance.