Lagging has always been the issues for everyone specifically in mobile, app size isn't that particularly big for so much features, but yeah mostly the reason of lag is whenever there is lots of peoples in a room and the room is kinda big, so it depends on room size and kbs of the scene, u may have seen many rooms put the limit of kbs.
Beta version is same as well it lags even more than mobile, but it works good and smooth if ur ram is high and processor is nice.
Classic one don't have this issue I think I never felt much lag in it.