Well, iPhone4 has just single core A4 processor, not even dual core. 4S has dual core A5 processor. But I get your point on the fluidity of iPhone.
I tried to point out several times on GSIII forum here that dual core S4 Krait is incredible beast of processor compared to any dual core AP from last year. It's built on small 28nm process and based on A15 like architecture. So it's actually running very close to quad Exynos in many benchmarks. But I keep seeing this questioned almost every week, lol. We are so obsessed with quad >> dual hype.
AnandTech - Samsung Galaxy S III Performance Preview: It's Fast