25% IR results on 56% more pixels. As this would lead to more cache misses in the GPU, it's even more than a 56% slowdown 
We have rewritten our shaders about a year ago. They are more accurate now, but requires a much better GPU, or you'll end with a lower IR on the same system. In the end, most mid-range desktop GPUs are fine to play at 4xIR, but mobile GPUs aren't as good :/
We have rewritten our shaders about a year ago. They are more accurate now, but requires a much better GPU, or you'll end with a lower IR on the same system. In the end, most mid-range desktop GPUs are fine to play at 4xIR, but mobile GPUs aren't as good :/