Yes it is small - normally R7 260X is 1/3 of R9 280X. I try it for a lot of algorithms X11, X13, Eterum and gives around 1/3. Only for quark gives a little bit more than 1/3 of R9 280X
I am trying to compare the characteristics of some cards, but do not understand what is crucial. Core frequency? At the moment I only understood that the frequency of memory and amount of memory are not very important.