Found the Fix for low FPS on PS4 :)

[FlasherIV 0]

I was ripping my hair off because every fix i tried didnt work as i continued playing terrible fps on GTA 5 online for PS4 , simply turn your ps4 off , hold the power button down on your console until you hear 2 beeps , one is initial and the other is 6-7 seconds later , let go immediately after the second and you should be in safe mode , simply select rebuild database and voila your FPS SHOULD be fixed...if not the next thing i can say is your hard drive is broken or your disc is corrupted.