I am a FF junkie and use it on all of my other machines, however, on my 2010 MBP 13", I've found that Safari uses far less resources and dramatically increases battery life while browsing (vs FF).
The only time I straight up "beachball" is when Engadget.com loads up...it's sad any way you slice it, for at work, we have ooolllddd XP machines with 2GB of RAM and they load 99.9% of sites instantly -- flash or no flash.