I doubt very much the problem is the version of Android and more to do with the bloat that Chrome drags around with it.
Even on Lollipop, my 2012 N7 is next to useless the minute Chrome has been loaded. The UI takes seconds to respond to almost any action, it's been in a draw with a flat battery for a month (another side effect of Chrome) waiting for me to put 4.4 back on it, I better be quick.