FailedToCreateDumbFile is largely due to low amounts of RAM, get 8 gigs and you will be just fine, but I THINK I still had it back when I was with 4 gigs however I'm not 100% sure.
I have 8 gigs of ram since the game launched and after WFA release performance went down the drain. Bugsplats became more prominent and performance in general went down south. Also the RAM related issues are still there, even for people that have 16 gigs of ram. There is simply memory loss all over the place in the engine.