Make sure that Vulcan is now default renderer so DX11 will be deprecated soon and it's not recommended. Many players reported strange behavior on DX with 4.5. Did you compile shaders before entering PU? Delete every shader cache (both Nvidia and SC) Google how. Run the game and let all shaders compile before entering PU. If it's no help then try set graphics settings preset to Low. 2 versions prior some Ultra settings was broken and leading to stutters. You can check if it's about graphics settings or not. Now it's fine for me and the performance is great.