There is not really "8" cores mostly 4 with hyperthreading wich i am not going to elaborate on further ..

But like i have said dont know whats happening in the app therefore my advice could be ignored..

Only possible advice that could be given is to find whatever eats away at your cpu usage and try to do less of that ..

This could be hard because it very well may just be as "less" as it could be i wouldnt know but do know that cpu load is not actually a bad thing though videos music and media as such typicaly are cpu intensive