To be truthful, this has been something I've noticed since way back in the OS9 days. In my office, for instance, all of the wimpy little PCs are simply "snappier" when it comes to the web. Pages load quicker.
In comparison, my Mac seems to take its sweet time loading webpages, no matter what browser I use. I wish I knew exactly why this was, but it's definitely there.
At least that has been my experience. YMMV.