Sorry for the clickbait title in advance but I wanted to give some input and some of my observations. I've owned macs for the past decade of all sorts. Recently had a 2014 mbp and a 2014 air. I realize there are exceptions and certain machines may have legitimate lag issues. But I feel the majority of the issues are because people are looking for it. They are looking for it because ever since the processor was revealed it has been a question in if it would lag at all. So naturally people are more critical and look for lag more. I know personally that every computer I've ever owned has lagged at some point whether it was a fully loaded MBP or a netbook. They all lag at some point under certain conditions. People just didn't look for it on their machines prior to this as much because the processors were not in question as much. I go back to my pro every now and then and it lags too under the right conditions. So in conclusion, stop looking for it and you probably won't find it.