The thing is, the iPhone isn't that fast, but it is able to react quickly to your input by showing you a nice, smooth but slow animation while work is being done in the background. As a result it feels faster.

That's something no other smartphone could do. I don't know how things are today but I looks like Android more or less "solved" the problem by throwing powerful hardware at it.

The killer feature is not really speed, but low input latency. And this is achieved by taking performance in consideration during development. And contrary to the old "premature optimization is the root of all evil" saying, you have to do it early, because while can be relatively easy to increase throughput, latency is much harder to deal with.

This is also part of the success of Google Chrome. While it didn't load pages that much faster than its competition it was great at showing you something quickly. It took ages for Firefox to catch up, and it looks like it did mostly because Chrome became slower over time. How is Servo going BTW?