Thank you for your feedback! Yeah, the game needs some performance optimization. It's my first real game created with a bigger Game engine (Unreal Engine 5), so optimization was a huge issue and struggle for me.
My guess is, that the volumetric lighting causes the low frame rate. For example, I did not bake the light, so the light and shadows are calculated in every frame. But since this is just a learning project for me to learn the basics of Unreal Engine, I probably won't update and further optimize the game.
But I still hope you had some fun playing and exploring the environment nonetheless!