Initial performance is likely poor due to default quality and settings being maxed out.
I'm going to be addressing these issues in an upcoming v0.1.1 patch release. To help improve performance on first load, I will be lowering the default quality level and making the Configuration window visible by default. Will also be disabling FXAA, Ambient Occlusion, and Post Effects by default under the Pause Menu.
Will aim to address a couple other issues as well that didn't make it into the first release. Release notes will be available in an update anouncement.