Does the 34 and 20 represent the number of tabs? If so, this is not a fair comparison, what with FF having 50% more open. But even if that number doesn't represent tabs, I am sure there can be websites that would put them much closer in performance.
Right now I have Chrome on my work machine. It has a 14 (again, not sure if those are active tabs or not) and it is eating 1.17 GB on my work machine. On my home FF (24) is eating 1.60 GB of RAM. FF is clearly using more RAM in each case, but it isn't slowing my desktop down any more than Chrome is on my work machine. I'd like for it to improve, but rather use something other than Google's tools on every single machine I use, I guess.