The physical storage of the RAM wasn’t just increased; the free memory given by the system has taken a major leap:
So why are these multipliers significant? Well, the more available RAM you have, the more you’re able to keep the background apps running. One huge difference I’ve noticed on the 3GS is that I can keep a bunch of Safari tabs open and when I go through them, they rarely need to reload. Anyone who’s owned a 1st generation iPhone or a 3G can attest to the fact that Safari would almost always reload each full page when you’d jump from tab to tab.
And a similar thing happens when you jump from app to app. One of the things that made the older phones feel sluggish was having each app fully load when you’d open it. But now with the 3GS and its larger memory, this is very much a thing of the past since many of the standard apps (Mail, Safari, etc) don’t unload so easily now. Because these are the apps that are used most often by people, this is one major reason that everything feels so much more zippy on it.
A 4X or 10X improvement is something I would appreciate in any of my gadgets, let alone my little iPhone computer.