Someone on reddit suggested vsync and I've added it to my list of things to add to the engine itself. Serializing data to save/load state is also in the pipeline, the engine is just very WIP at the moment.
The high GPU usage is probably for the background, and disabling special effects should make that go down tremendously. The background is actually a slightly modified version of this shader on a flat plane, and if you read through what the shader is doing I think its understandable why it'd use the GPU as much as it does. I'd made the decision to use it because I thought it looked nice and the game still ran at many hundreds of FPS, but I added the toggle to disable it in case lower end PCs couldn't get to a reasonable framerate with it on.
Thank you for playing the game :)