I changed the rendering engine from GLES3 to GLES2 and corrected the color changes in the Environment Node. This little change by itself has tripled the performance of the game.
I added, yet again, allot of the unused assets I made for the game before I originally released it. I don’t like leaving assets and the effort invested into those unused.
I also changed the Depth draw mode to “opaque only” of many materials. This ensures that the finer details and transparency of those materials is visible now.
I additionally learned how to give my Godot games FPS counters and added the option to activate a little FPS counter in the upper left corner of the screen by pressing the wheel button of your mouse. You can activate the FPS counter this way and deactivate it again.
I yet again gave the Steam page new screenshots of the game since the change to GLES2 has changed the color end result a bit.
This is the biggest performance improvement I made for this game until now and all it took was changing one single little setting for the performance alone.