I have noticed some intermittent slow downs but I'm playing a single player game, they haven't made the game unplayable, and as such generally haven't gotten that far into monitoring the game performance yet. What little I know about the UPS though, I suppose it could be...I haven't really paid attention to what the lights were doing when that happened. I will say that lamps seem to be more susceptible to not having enough power than other items. I'll notice a lamp flickering before I notice an inserter slowing down. If you're running close to the limit or have something that intermittently spikes the usage like a roboport (charging robots) you might think you're ok and just miss it. I have a small remote section of my base that was doing just that. Power was close but generally seemed to be fine and I couldn't understand why my lights were flickering. I had recently made a few changes and added more production capacity just to be sure but was still having problems. I just happened to be looking at the power grid when a bunch of robots flew off, did something, came back and recharged and I saw the spike...I had given myself about 5MW of headroom and the charging spiked around an extra 10MW...added even more power production and problem solved.
