Hello to all! Recently I bought an iMac 2017 27 inch with i5 3.8Ghz 24gb of RAM with the radeon 580 gpu. Immediately when I load chrome and firefox and went to watch youtube videos I notice some serious stuttering on both 4k and 1080p videos. Safari at 1080p looks ok, Also when I tried screenflow to record my screen while playing 1080p youtube videos at full screen the frame rate of the produced file is low as hell. My 2012 mac mini does it completely smooth which doesn't make any sense to me since all of my iMac specs are at least twice as good compared to my mac mini. Besides videos I do notice lagging on any apps . like my IDEs when i scroll a document - i am a web developer. or for example when i post a message on skype the effect it does when showing the message on the board is supper laggy. again battery smooth on the mac mini. Cinebench and geekbench didn't show anything bizzare. I did try both sierra and high sierra and I have the same stuttering effect on both of these. On all of these scenarios cpu and ram are low although cpu was at 40% when I watched 4k youtube videos. Overall I do notice lags here and there which are no justified by any means. Does anyone else experience anything like that? Thaank you.