this happens with all of the phones.if s9 arrives then they'll forget s8 like the did it with s7.they shouldn't do that, after all from s7, s8 has come.
yeah right I've played nfs, asphalt 8, and other high graphic games. and it runs smoothly but some games lag too much. now should we call it hardware problem or software problem.
even I faced the same problem a few days earlier I tried to delete but it wasn't but I deleted the pics individually it got deletedhope this works with you