Quick answer: Godot 4 canvas mix rendering many transparent layers showing overdraw warnings? Each transparent layer adds overdraw; combine via baked sprite or use opaque where possible.
Boss arena with 8 transparent backgrounds; framerate drops on integrated GPUs.
Bake transparent layers
Pre-combine into one sprite. Single draw; no overdraw.
Or use opaque where possible
Convert pseudo-transparent (mostly-opaque) to opaque. Engine sorts; less overdraw.
Profile overdraw
Debug > Visualizer > Overdraw. Red = many layers; target reduction.
“Transparency is expensive. Combine where you can.”
If your 2D scenes are slow, the overdraw visualizer is the first check. Target the brightest red.