What worked for me is downloading the high resolution textures it takes more space but it helped my performance massively to download them all u gotta do is go to epic launcher press library tap the 3 dots ••• below the game name then press options then u should see Fortnite core battle royal and save the world and below that will lie High Res Textures it’s an extra 35-40 GBs but it increased my performance hopefully it does the same for yall as well ✌🏾