My bad, you are right. I should spend more time with the profiler I guess xD
As for Direct3D 12, for MSAA an extra render target is needed as support only the flip presentation mode, which unfortunately does not support directly multi-sampling :\
Another "bad" news of D3D12 is that ASTC compression support will not supported in this version of DX12, I guess it will probably added in a next minor iteration of DX12, maybe focused on mobile hardware too (Qualcomm where are you?)
ASTC is already optional in DX12, besides you already have other compression formats to work with. The real benefit of ASTC is outside of the D3D universe imo.