I think most of the blame is to place on the software side and the abuse of jscript by web developers without any added value to the user experience. II have a lenovo thinkpad x200s (low voltage 1.6ghz core2duo) with an SSD and browsing+office work (office 2010) runs absolutely fine on this machine.
I'm using linux with xfce (very light on resources) and heavily customized firefox with noscript, adblock, viewtube (no flash needed, it decodes through the vlc plugin 15% cpu vs 50-60%), both the cache and the browser profile are stored directly on the ram (synced every 30 mins or so).
It has a slight lag while loading a web page, but it doesn't feel frustrating or SLOW by any means, you wouldn't say that this machine was running such a slow cpu.
To make matters worse for the poor cpu I'm even using full disk encryption (getting your laptop stolen with dozens of passwords on it is a hassle).
Baytrail/Cherrytrail would be a significant upgrade for me since on top of single threaded performance increases I'd get another couple of cores, encryption instructions (baytrail has them right?) and even hardware accelerated h264 decoding!
TLDR the right software and system tweaks can go a long way in ensuring you can use your hardware for many years after your purchase, BTW turning off jscript on most of the pages I visit improves my experience further.