During this research, which, by the way, was quite extensive - 45 000 separate tests conducted on 1000 different web pages - it was found that on average the Android browser is 52% faster than the iPhone 4's one. Moreover, during these tests Google's mobile OS managed to load 84% of the web pages faster than iOS. Really impressive.
Even Guy Podjarny, the CEO of Blaze Software - the company that conducted the study - expressed his surprise at the results:
This is a quite comprehensive test, so you can't really argue with the results - turns out, Android's browser is much faster than its iOS counterpart, although we are not sure how many people have noted this, which is, you know, the only thing that really matters. Moreover, chances are that the guys at Blaze Software tested high-end Android devices, so if you have a mid or low-end handset powered by Google's mobile OS, it's very likely that you won't get the same results.
source: Blaze Software via BGR