BF4 and HT on gives some strange results.
"Our last test, and the last chance for Windows 8.1 to redeem itself...and wow, Windows 8.1 comes out guns blazing!
We actually give you some extra data here, with our standard tests on the left side, and modified tests on the right side of the graph with Hyperthreading disabled. Much to many of our readers' amazement, we previously found that Hyperthreading actually hurts performance in this game, despite BF4's reliance on multiple cores, and so we test BF4 both with and without HT enabled on our 3770K. No surprises here, at least from our viewpoint: Hyperthreading does not work in Battlefield 4. Using it hides some of the benefit of Windows 8.1, but with it disabled, we see positively huge benefits to running Battlefield 4 on a Windows 8.1 system! We're talking a 24 percent boost at stock clocks and a 16 percent boost at our overclocked setting. Now, there's no getting around the fact that recording data in a multi-player round, particularly in the chaotic Siege of Shanghai level used here, is very hard to do consistently. We conducted multiple 30-second runs and averaged them to get our data, and tossed out every sequence where we were killed during the run, which throws off the results. We should also note that Siege of Shanghai is not only the toughest map in the entire game, performance-wise, but that it's most demanding after the skyscraper falls. So of course that's the test we ran, always on a full 64-man server, always at or near Flag B on the map. Lots of variables to keep in mind here!
Rest assured, this is not a benchmark we enjoy running, and frankly, in future articles, we probably won't use the Siege of Shanghai level. It's too chaotic, and performance changes far too much depending on where your character is on the map. But there's no denying that based on the number of runs we conducted, it's obvious that Windows 8.1 is simply the better operating system for this game. In fact, it seems that Windows 8.1 on its own provides more of a benefit in this game than our 22 percent CPU overclock, and that's saying something. Also keep in mind that at many times during our benchmark runs, our video card was pegged at 99% utilization, meaning that this is not strictly a boost in CPU performance. Windows 8.1 may be working some kind of magic on both the CPU and GPU pipelines in this game. Given the rumors at the time of its release that Battlefield 4 was the first game to truly leverage the enhanced efficiency of Windows 8.1 (and specifically the latest version of DirectX), it's possible that this game is in fact a window, so to speak, into the future of gaming performance under the new Windows OS."