I have the same issue, there is a lag spike every second like clockwork in many games, especially those that use VR headsets. This is on a NVIDIA 980 TI card. It took me awhile to track down but it's definitely flux doing it, I can reproduce it 100% of the time.

@Tungsten_smooth Thanks for the quick reply. Yes, I checked movie mode - it is almost what I want, but the problem is that I need to remember and manually set it. It's no big deal for me and I can get used to it, but I would always prefer it if it was a "set it and forget it" setting.