Thanks for trying it out!
Yeah i can see that there are some issues...
What's your PC setup like?
And yeah i forgot to turn the backface collision on the grid, thanks for pointing that out, i'm fixing it right now
It's 4GB RAM bad. I think I'll have replace it soon. I doubt anyone here has a worse PC than mine, but my suggestion is to add an option to disable some shadows/shaders or reduce render distance for low-end computers.