Right now I am on the beach again on a new profile, and it seems ok, but I will enter Cyseal and walk to the exact same spot. Maybe it has something to do with my savegame being old? It is more than a year old. I will test it and report here. It is not a big deal for me anymore, as I started to play the enhanched edition on the Xbox with someone, which is more fun

The alpha version of Original Sin 2 runs much better on my hardware, so that is also a big plus for the upcoming game!
Edit: Oops forgot to mention: I tried other games and they seem to work fine. I tried Grim Dawn, Doom and Civilization 6, no problems with the frames.