This lag/delay issue really bothers me a lot. It is very noticeable, especially when moving mouse cursor. I think at least 1/10 of a second. Does anyone know how to solve the lag/delay on second monitor connected via HDMI port? It happens both on my macbook pro 13" (late 2013 base model) and the new 2016 macbook pro 15" (using a HDMI 4k adapter). After searching a lot on the internet I couldn't find a satisfactory answer. First I though the issue was related to my 2011 Samsung 3D Plasma TV, but I recently bought a 2015 4K LED TV from LG, and the LAG/DELAY is exactly the same. Could the issue be related to poor TV hardware for this purpose? Maybe they don't happen in good computer monitors... Since I don't have one, so I can't test that, and I would appreciate if someone have any clue on this.