Turn Gamepad on before game starts
Click on the game to get the focus
If you experience slowdowns be sure you are using the primary GPU, not integrated, test in other browsers or download, it's available for Win/mac/linux.
Steer: Left Analog Joystick
My Record for reference:
5.233 (Without touch grass)
Grass decreases speed but taking a bit at good moments can give you better time.