I'm using Ubuntu 16.04 with XFCE I enjoy playing Factorio in spare time. When I run it on the laptop monitor it works great, CPU usage is high and it is turbo boosting. When I connect a display over HDMI and play on it, it works worse and has huge droops in FPS from time to time, CPU usage is around 20% and it is running at a mere 0.80GHz
Note: For those thinking that the cable is the problem: the cable works fine in Windows and while doing anything else. It is a gold plated HDMI 2.0 cable. I have it connected with an adapter from mini Display Port 2 to HDMI 2.0