Now for the tests themselves. The battery life test that started this story off is the one included in Geekbench 3, which according to Primate Labs' John Poole does include some idle time but is generally very CPU intensive. According to the Xcode Activity Monitor instrument, the Geekbench 3 battery life test generally keeps the CPU pegged between 55 and 60 percent load for the entire time it runs, with occasional dips below 55 percent and peaks above 60 percent.
Update: To clarify exactly what Xcode's Activity Monitor is telling us, remember that every logical CPU core is tracked individually, so for a dual-core CPU like the A9 "full utilization" would so in the dual-core A9 full load is 200 percent, 100 for each core. The Geekbench test is putting about 30 percent load on each core for a total of 60 percent. For comparison, the relatively light but modern iOS game Shooty Skies oscillates between 30 and 70 percent depending on how many objects are being drawn on screen.
Our WebGL battery life test similarly keeps the CPU (and the GPU) working continuously, but at a slightly lower level of load. CPU load for this test typically hovers between 45 and 50 percent, and the GPU Driver instrument says the GPU utilization is between 25 and 30 percent. We also ran the GFXBench GL 3.1 battery life test for good measure, which loops the "T-Rex" test 30 times while measuring performance and power drain. These two tests approximate the load that a 3D game might put on the A9.