I'll start by saying prior to doing this the game played decent enough before Orcinium, then down hill from there. Now on my wife's pc with GTX 750TI and even my GTX960 FTW has shown excellent improvements both in this game and Batman Arkham Knight - which has been patched up a lot for performance. Hoping this comes in handy for at least one other person
Not sure how to go about this with Radeon. I'm sure there is some specific setting or something like this one that would help. Had issues with my R9 270 before I shipped it to a friend and it ran like poop which it shouldn't have. Don't have it anymore so anyone with Radeon cards please chime in if you know the related setting on that.
Steps:
-Open NVIDIA Control Panel (Not NVIDIA GeForce Experience)
-Go to 3D Setting -> Configure Surround, PhysX
-Change PhysX settings processor drop down from Auto to your Graphics card
--Mine stated graphics card was being used already while it was on auto, but apparently I had to specify anyway.
That's it. Staggering lag in all zones, crowded or otherwise disappeared. Ultra settings on 960 smooth and surprisingly the 750TI was smooth-ish on high settings. Found this fix this morning prior to DB patch and had no issues even after patch. And like I mentioned above, I seen an FPS increase on Arkham Knight as well. Wonder how many games I've played could have been improved by this.
I since have made the improvements, everything is working better including OC, nvidia settings tweaks, etc.
Enjoy