2010? So that's 2gb of ram and El Capitan can run smoothly on that?! My 2011 Air 11 is still on ML, worried it'll slow down with the newer OSes. I should update!
I once had a 2008 macbook aluminum and it ran smoothly on el capitan, i was even able to bootcamp it and install windows 10 ... So i'm sure a 2011 machine can handle it even more