It’s possible that lower-end CPUs would see different results in these tests. As we’ve discussed before, DirectX 12 doesn’t really help you recover much in the way of GPU performance, though features like asynchronous compute can improve GPU perf in certain ways if supported in hardware. The major advantage of low-overhead APIs and the place where we always saw them do the most good was when paired with low-power or weaker CPUs, not GPUs. Here, they can make a significant difference, sometimes cutting CPU utilization by 10-30 percent and allowing for corresponding improvements in power consumption or giving developers more flexibility. We’ve also seen some specific cases where AMD’s DirectX 12 performance has given it better competitive standing against Nvidia, though again, the shifts here tend to be on the smaller side.
But at least in WoW, for now, the message seems clear. If you have a higher-end CPU and reasonably new GPU, DirectX 11 is the better API. We’ve got an eye on the situation and will re-test and/or revisit this question if Blizzard makes any formal announcements about improving the newer API’s performance relative to the older one.