My 2012 MacBook Air (with SSD) is still running as good as it did when it was new. It's really amazing that a computer that is eight years old runs so well.
Review: 13-inch MacBook Air (mid-2013) - 9to5Mac
Apple MacBook Air review (13-inch, mid 2011) - The Verge
Apple MacBook Air 11 - Mid 2012 Reviews, Pros and Cons | TechSpot