Hey there. Fellow Gamer with potato PC here. I actually get this issue a lot with Unity alpha builds. It's not as optimized as it could be. so what you need to do is not only change the settings, but possibly put your build in the 1000x700 range of resolution, turn shadows, fog, and SSR to the lowest settings, and set your graphics quality to medium (anything lower and you can't read the pages. if this isnt a problem for you, run it lower.)