ram. there is extra ram applied to load in the resource pack which means a tiny bit more power useage overall. a real cilent truly improves the fps by actually modifying the game in certain ways (mainly coding) like lunar cilent. which changes the behaviour of the third person camera, or optifine which adds new features for better optimization+shaders, those took actual coding to make and unless somehow you can alter the code of MCBE then fps optimization isnt really possible at all (except for rtx sorta cuz the upscaling just downscales the base resolution and passes it through a filter to sharpen the image and make it 2x sharper which allows the game to run quicker)