FPS drops on gtx 970. Patch?

I faced the same issue when i was playing trial versian. The first patch didn't solve this issue. I have 4k monitor, my graphic card is 1080ti, I use SSD. Initially I had a suspicion that my PC isn't powerful enough to run this game in 4k on ultra settings. But on the other hand few weeks ago nvidia released trailer of 4k gameplay with 60 FPS on 1080ti. So I began to doubt that the root cause in my PC. And after that I noticed that at the day time FPS drops quite rarely. But at the night time FPS drops significantly, especially when street lights are turned on. I assume that street lights consume a lot of resources which causes FPS drops and stuttering. I hope that next patch will solve this issue.