I have 2 laptops (a slow one and a fast one). On our home network, I notice web pages pop up quicker on the faster one even though both use the same DSL hookup.
So, apparently this is caused by the faster processor rendering the graphics quicker. While I no longer have my old 3G to compare to the new 3G S, I believe the 3G S does bring up pages quicker.
However, we're only talking about a few seconds at most and hardly reason to replace a 3G IF that's the only reason you're thinking of getting a new 3G S.