My 2010 MBA is on it's last legs. I don't know if it is a hardware issue or it just cannot handle Yosemite. Time for a new machine. I'm debating getting a 2014 refurb with the 8 gb of ram, or a 2015 machine. There is a $300 difference. I really don't care about force touch, I'm more concerned about having a machine that will last me another 5 years.