Going from a 1, to a 2, then to the 3, I would put most of the blame on Safari crashes on a lack of RAM. Using the same iOS version on both the 1 and 3, the same page would choke on the 1 and load fine on the 3. Though this is mostly anedoctal, I believe others have had a similar experience. I'll add that going from a single to a dual core also helps Safari performance.
Additionally, 1GB RAM makes for a much nicer multitasking experience. It swaps apps without reloading more often - and results in smoother app switching. On the performance side, the CPU does run at a higher clock rate [than the 1], not to mention a higher performance GPU (aside from there being four of them).
And don't get me started on the 3's display 😀