Thank you for playing! It's entirely in GDScript. I did take the extra effort to make sure the performance was as good as I could make it. For example: almost all sprites in a level aren't rendered unless on screen. That helps a lot because each level has thousands of sprites. Enemies are also in a dormant state in which they execute no logic until they're on screen too, then reenter that dormant state if off screen for too long. This also helps a lot with performance to prevent too many physics calls each frame.