Trying to stream various 4K video files from Youtube and other sites however every one of them lags and is really choppy under OSX. My CPU maxes out and it starts to lag. I plugged the laptop in to see if that made a difference and it still lags. Specs: Newest 13" rMBP base i5 CPU, 8GB RAM, 256GB HDD, Maverick's with all updates complete. Am I missing a setting somewhere? Latest Flash player installed as well. Tried Safari and Chrome, same issues. No other programs running besides a web browser with a single tab open with the video. Comcast 25mb/s internet speed with no router issues. Surely a $1500 laptop can stream 4K video! No? I can play downloaded 4K videos just fine, but I want to stream them and save the space on my HDD. Any input? Thanks.