If you are not into multiplayer, then try patch 22.214.171.124, as it is the last patch with the older shadow system, which imho is better than the latest on high or very high settings. Also, it is not out of register like the newer one and some find it gives the best performance.
If you are talking about mods, like enb series, then they all either sap performance or cause glitches, in my experience. Get the game running well without them and add later on if you are keen.
For me, a good PC experience is HD graphics, fast frame rate and very little stutter or popin.