Autumn Aurora 2 it's modification made by small group from Poland which brings the autumnal atmosphere to the Zone and totally overhauls the graphics, audio and gameplay of S.T.A.L.K.E.R. Shadow of Chernobyl.
My recommendation about playing in AA2.1
-no health/stamina/ammo bars
(above options you can find in the package with mod in #Mod Options directory)
-disabled SMAA in SweetFX.txt and EdgeAA in enbseries.ini. I'm using x4AA forced in Nvidia drivers and yes, I don't have DynamicDof, but the overall image is so SMOOTH (especially trees in the distance) and I don't regret it. No grass/trees flickering, all edges are so smooth. I highly recommend it.
If you want to dramatically improve your performance, delete all "level.details" files from Gamedata/levels. The grass won't be so high but still dense and your performance much better.
Let the tests of upgraded AA2.1 begin.