That's a really good point, yes I use some rendering to make the game look a bit better.
I'll add more options to enable / disable all of it and, like you said, lower the shadows so it can run on a wider range of devices !
Thank you
Viewing post in Project P.I.T.T. - Demo comments
Btw, I don't know whether your game will be released before this or not, but Godot 4.6 is releasing soon with better support on DirectX (for Windows), which means more windows users will have slightly better performance and less graphical issues. If Godot 4.6 releases by that time, you could consider it, it might solve the issues you see in the comments with certain people having graphical bugs and low fps.
Also, one more tip, changing the window size isn't going to increase performance because it only changes the physical window size. Look up get_viewport().content_scale_size.
This will change the actual viewport scale which will improve performance when lowered.