Hi, I'm wondering if the app consumes a lot of energy? The battery time of my pc has shortened since I installed the f.lux app.
Not for me, but it could have some slight effect. According to Activity Monitor, it consumes about 0.1% of my battery. That's only on 3400K, though. Could have more of an effect when you use warmer colors.
It shouldn't, but I notice that you're running an older OS, which sometimes might have less efficient video drivers.