Performance drops when using with drei>Reflector

[gsimone]

Demo here: https://codesandbox.io/s/fo7fg?file=/src/Scene.js

<Reflector /> uses this example https://threejs.org/examples/webgl_mirror.html

[drcmda]

reflector is quite expensive, i think it re-renders everything again (?), not sure how these two interact otherwise.

[vanruesc]

Related: https://github.com/vanruesc/postprocessing/issues/219#issuecomment-668572380, https://github.com/mrdoob/three.js/issues/19248

The performance issue is most likely caused by three's outputEncoding system. Reflector probably triggers shader recompilations each frame due to alternating output encodings (e.g. renderTarget uses LinearEncoding, screen uses sRGBEncoding).