First of all, the textures. You can save the texture with BLP Lab program on 70% quality with opaque selected without losing much and another thing - you need to remove the animations that are not necessary and with animations it is a little bit complicated, you would need some knowledge on the matter, perhaps read up on it, because I never succeed in removed them properly. it is not enough to delete the animation on model editor, it just stays hidden that way. So if you did these, its size should do gown drasticly.