For a 'typical' aerofoil at cruise speed, not much
What is "not much"?. For a typical aerofoil drag coefficient increases quite a bit with angle of attack (assuming constant speed) at typical angles of attack flown at cruise, even your own graph shows it. By the way - heavier load hits your pocket book, someone calculated that in typical airline flying a heavy male passenger (117 kg) costs airline about 65% more in fuel than an average 73 kg passenger - again cost attributed to extra drag.