Sorry to hear that; I would recommend lower settings (it still looks great) and setting your resolution to 1080pi if it's higher; this should fix your FPS. The settings do change but there's a ui bug in this version that resets what's highlighted once closing it out.
We've actually been working on a brand new version of this demo that solves a lot of issues we've heard from our community. This includes a rehauled lighting system, a tighter story, more scares and better optimization.
We'll likely release it on this platform but we're going to prioritize our steam page once it's out. We considered taking this version of the demo down but so many people wanted to play it that we decided to keep it up for the time being.
We'll let you know as soon as the newer version is out! We apologize again!