Isn't that just LOD, and is done regardless of whether dof is enabled or not?
I don't really like DoF anyway :P
What?!? No it doesn’t. It uses the depth buffer to progressively box blur or gaussian blur the frame post-render.
https://lettier.github.io/3d-game-shaders-for-beginners/dept...
Nowhere are they replacing models, replacing textures, or anything of the sort. I suspect the issue here is that box blur with a sampling of 3x3 is exponential performance hit at 4k vs 1080p. By a factor of 8x due to the extra sampling lookups.