I run firefox on Fedora 20, on a dual core AMD64 from 2005. It worked ok with 1GB, but as indicated things went south when it ran out of memory. I upgraded to 2GB and useage rarely goes above 1, so everything is fine now. That said, I'm not one of the people who use tabs instead of bookmarks. My expectations are probably lower than many too, but I am all too familiar with content in one tab destroying performance of the browser as a whole. So I'm all for this e10s thing.