i downloaded the game and when i play it is much much slower than the trailer, seeing that the only way to change raphics being resolution\aspect ratio, i want to know the best performing settings, does it need to be in fullscreen or not? and so on.

There are no performance options, I've optimized everything as much as I could (it barely ran on the potato I developed it on either...). For instance AI drivers have a very simplified collision checking to save resources, which is why they clip through the ground a lot - I figured nobody would notice when there's 30 racers. (But if I simplified it further it would go from "kinda buggy but not too noticeable" to "unplayable"...)

The one thing that could be an issue is if you're on a computer which doesn't have a GPU (i.e. the CPU does all the rendering) - a lot of the optimizations boil down to "let the GPU do as much work as possible because it's faster" but it's a bit counterproductive in those cases.