F.lux causes screen jerkiness. Games, videos, animations... are not smooth. Tested in multiple systems.

  • Hi,
    I'm a huge fan of f.lux but I have had some serious headaches trying to find the source of one particular problem.
    I've recently bought a new computer but I was experiencing some serious media playback issues not usual for my specs. Smooth scenes in videos were laggy, jumpy and jerky in a very distracting and annoying way. This made me very frustrated because my movies were being affected by it and I didn't know how to solve it. Later on I discovered that Youtube videos, smooth animations and even moving screensavers were also affected by it, so it seemed that the problem affected anything moving in the screen.
    I contacted Intel support and I gave them all the details of my system, the software I used and also a video of my problem. After they couldn't help me any more I created a thread in Superuser forums and asked them for some tools to find the source of the problem.
    Thanks to a testufo webpage they gave me I discovered that f.lux was affecting every movement on my screen even when the "disable until sunrise" and "disable for 1 hour" were enabled. The only way to have smooth scenes was to completely close f.lux. Now that I know it I'm quite happy to enjoy my movies again.
    The page contains two moving ufos. They should be moving smoothly across the screen without any jerky movement or pause, but that is not my case when f.lux is loaded (even when it is disabled). Now imagine how distracting it can be if any moving scene was repeatedly pausing and skipping a few frames throughout the whole movie at a rate of one time per second. This is obviously not a problem while working with documents or viewing webpages but it is when seeing some video inside a video player or in the web browser.
    I tested it in 3 systems (one of them described in the Intel forum, the other ones described at the end of this post) and the behavior is the same in all of them.
    There is also a second unsolved problem that I described in another f.lux thread that makes some systems unresponsive while it is transitioning colors. This makes the system unusable for some extra 20 seconds after it boots up at night or just at sunset time. Entering movie mode does the same.
    Hope I can go back to using f.lux when these problems are solved.
    Just tell me if you need any more info.

    PD; My other two system's specs are:
    PC1: Windows 8.1 64 bits

    • Intel i5-750 cpu
    • Ati 5770 HD Sapphire Vapor X
    • 4 GB ram 1333MHz

    PC2: Windows 8.1 32 bits

    • Intel Atom N455 cpu
    • Intel GMA3150 gpu
    • 2 GB ram ddr3

    PC3: Windows 10 64 bits
    -Intel i5-5200U
    -8 GB RAM DDR3

    Edit 5 months later: I think this is not getting enough attention because many people didn't bother to search for the source of the problem or they gave up searching. The problem still happens as of today.

  • 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.