Guessing you don't use Android or at least haven't in awhile? I've been Android user now since the release of 4.0 and it seems much more responsive now than my wife's iPhone 5 in almost every category from web browsing to gaming. I was very aware of the lag pre-4.0 and that was the main reason I never switched (was an iPhone user before that). Now it's as smooth as can be.
... with one glaring exception: on my Android phone, at least, pressing the home button very often takes a good 1-2 seconds (sometimes more!) to take you to the home screen, with no visual feedback that it's doing anything. A second with no feedback is an eternity in GUI time. iPhones (and iPads), on the other hand, respond pretty much instantaneously to the home button.
I'm pretty used to this behavior, so I know to just wait, but it's still pretty annoying (one hits the home button quite frequently in typical usage).... Even if there's some property of the Android software that makes it challenging to do the switch itself quickly for some reason, couldn't they have at least provided a little visual feedback that it's doing something...?!
It has gotten much better, most certainly, via things like concurrent and partial garbage collections (and the improvements in the integer-units in the CPUs, simply brute forcing through these UI thread impediments), and other core improvements, but it's still most certainly behind iOS (where UI priority was a core architectural concern from day one).
Aside from a still not silky smooth experience, Android still has an endemic problem with completely non-responsive interactions -- you click or do something and everything just stops with absolutely no hints or feedback....and then three seconds later a result appears.