So long story short. Since act started I played 11 games with 100% wr and with decent scores and yet I get 16 \~ 18 RP? Is this normal? I'm gold 3 and even against Plat 3 / Diamond players, I get that. Also, the performance bonus is a jok...

It just encourages egoistic players to be more toxic and unhelpful to teammates. Simply displaying at the end of the game/post game scoreboard would suffice.