Computers have different speeds, and the same software still runs on them. (Unless the computer's too slow or the program is sloppily coded, but then that's the fault of the manufacturer or programmer.) Why do you think a framework should iron out performance differences?
I specifically don't think that. My comment's grandparent mentioned performance differences between browsers, and my comment's parent suggested that a JS framework could smooth out differences between browsers. I was pointing out precisely that a JS framework wouldn't be able to compensate for that.
