kernel-task taking %200 of my cpu while playing league of legends

as my title, i used to have heat problem with my 15' macbook pro early 2011, but recently it just got worse and worse. and i just found out when i am playing league of legends, in the beginning lol will take up to %100 of cpu

then kernel_task cpu usage will increase dramaticly up to %300,

after i exit the game, both apps' cpu usage will decrease, kernel will back to normal, as for lol client, %10 when im leaving it alone, increase up to %80 when im clicking any button.

what is wrong with this? how can i solve this? anyone could help me please? thank you so much