I'm having the same issue on a Radeon 250x, thought my GPU was dying (Same glitching happened on my last one in other game before dying), although I'm glad to know that's not a hardware problem it does get annoying from time to time, furthermore, I've been having performance issues in places where I didn't used to, for example, I get huge FPS drops on the main square in the promanade, it would seem like a AMD realated thing.