I bought the 8/256 at release last year and wasn't too impressed with performance. It was pretty laggy. Has this been fixed? I've been thinking about getting this again through refurb. I since have gotten a base Air 13" and wondering how the Retina performs in comparison to that? I understand that the extra pixels requires more performance. I will be using garageband/logic pro extensively and really want better UI performance, not worse. Any complaints with Yosemite (animations, UI lag) so far? Running at 1440x900 ideally.