I just got my rMBP 13" Early 2015 2.7GHz, 128GB a couple of days ago. It's running El Capitan 10.11.2 and display scaling is at the standard setting. No external monitor connected, cpu temps are completely fine. The UI is very smooth, scrolling and animations are all 60fps or very close. But, every like 30 seconds or so there is a lag of what feels like 0,5sec where everything stops, text input, scrolling and animations. I can manage to write an entire word, and nothing appears, then after the 0,5 seconds the word appears as a whole. Also, when scrolling, the scroll stops for the same amount of time before it suddenly starts going again. Does anyone have any suggestions as to what this could be? It doesn't really affect my workflow, but it gets annoying after a while.