oC wise, the iPhone 4S A5 powered chip is the most powerful of all the three phones. The iPhone 4S has a 800MHz dual-core Cortex-A9 based processor, while the Galaxy S2 has a 1.2GHz Exynos 4210 processor. The Galaxy Nexus has a 1.2GHz OMAP4460 SoC. The A5 inside the iPhone 4S packs a PowerVR SGX543MP2 GPU, which is the fastest powerful mobile GPU on the planet right now. While the ARM Mali-400MP GPU is not as fast as the PowerVR GPU inside the A5, it still is the fastest mobile GPU to be found inside an Android phone.
while your right, I am pretty sure ICS doesnt potentially need a faster one than the 4s. The reason for the 4s having that is based around IOS
correct me if I am wrong