My friend's brother got an ATAR over 99 and got state rankings. All he did was become organised and didn't stress.
He only did a few set hours per day of studying. Not all state-rankers are crazily into their studies. Chillax !
It depends on the teaching methods. If the teachers at your current school can't teach, then by all means move schools.
Take in mind that you have to start all over again in aspects of friendship and school environment. Ranking means a lot in the senior years as well !