I have a late 2010 13" Macbook Air (2GB, 128GB SSD). I "upgraded" to Yosemite last year, and regret it. It's much more unstable than in the past, and while when I first got it I barely remember seeing the spinning wheel of doom, it's now a frequent visitor. I noticed a marked performance drop after the upgrade. I'm not ready to upgrade yet. In fact given what I use it for (light web browsing, Pages, some light web development in Textmate) I essentially intend to keep it till it dies. I am therefore thinking abut downgrading. My question is, how far should I go? Should I just go back to Mavericks, or might I as well go back to Mountain Lion? The Mavericks upgrade is long enough ago that I can't really remember whether there was much of a difference between the two performance-wise, so am interested in opinions. From a features point of view, i can't think of anything that I'd miss, and I don't use any software regularly that won't run back to 10.7, so it really is just about what will perform best.