RFX_Initial Storage

What does this do and what shaders depend on it?

In the config it says if you leave the initial storage and depth buffer at 1, it will automatically disable either of these depending on the shaders enabled. I'm only using Tuning Palette LUT and LumaSharpen and the storage did not automatically disable. If I manually disable the initial storage, I get a substantial FPS boost and the image looks exactly the same. The FPS boost depends on the draw calls but when they are low, the FPS boost is insane.

If the initial storage was necessary for the shaders, should there be a FPS boost with it enabled? I tried some heavier effects that require insane passes, such as GAUSS and there was still no reason to enable the initial storage as it resulted in lower performance and no difference in image quality.

It's used in shaders that need to get the original game image after several passes were already applied to it. LumaSharpen and the LUT shader are not one of them, so you can safely disable it and get a little of extra performance from doing so.