Can't reach full speed on android

[horiman]

Hi i have same problem on my Honor 9. Im trying to get full speed in GTA LCS. On android 7 i have around 30 fps even after hour of gameplay - totally playable. Now on Oreo after 2-3 minutes FPS drops to aroun 20 and game become unplayable. I check with CPU Float and only little cores are active. I tried different versions of PPSSPP but its still the same even in different game. So the problem is definetly with android 8.
If someone knows the solution of this problem ( except downgrade to android 7) please let me know. Thank you