I don't know if this is true or not I only saw it for a spilt sec, I remember dying and my camera clipping under the map for a sec and seeing a bunch of water. I dont know what map. but if there is just a bunch a water textures under the maps, maybe replacing that with just all black or something to help with performance. just an idea. again idk if the whole map just has all water under it as a filler or it was my game bugging out.