Check the spoiler. Or is that TLDR?
Damnit, sorry I missed that

iBlurDeferredShadowMask=5 - wee bit taxing, you could get away with 3 or 4 and visually its almost the same, this is for your indoor shadows any ways which are already pretty darn good as a default.
iMaxAnisotropy=8, almost no impact to performance so you can either set it directly to 16 here or better yet drivers do a better job so in the game's profile just over-ride and do the x16 there instead (better water).
iShadowMapResolutionSecondary=1024 - put this guy up to 2048 as well, little bit more memory but for some reason I've always gotten better performance out of the shadows by giving them more memory like that (within reason)
bTreesReceiveShadows=1 - swap this
bDrawLandShadows=0 - with this and experiement, both are heavy but land shadows may give you more visually available niceness then random trees have a dark spot on them.
As mentioned you're missing some critical ones too like the fShadowBiasScale (rec try at .25) & iShadowMaskQuarter (recommend 3, this is the same as defferedshadowmask but for the outside)