Hi!
Thanks for the comment! Due to the pixelisation of the rendering it improves the framerate (depending on the resolution you want ).
The pixel art effect is not working via post process so I'm not sure how to subtract an object but maybe via the render target flair?
But in any case if the object is already in pixel art you should pixelate it again in order to keep the visual coherence (2 different types of pixel art on the same screen would probably look weird)