Welcome to the forum m8.
It’s a great list with problems ps4 has in this game, but you can play, not as we should yet we can.
2 things you must do for sure are…
- Performance mode.
From your starting menu you can choose quality or performance, so forget quality, prepare your self for nasty textutes, slow rendering and all that comes with this choice, but it performs way better. - Turn off the journey steps.
This you can do on the playing menu, you’ll find it very easy. I know it’s helpful to see your next step of your journey step but it creates horrible lags. Imagine that i deleted 3 times in a row the game and download it again, just to understand what @Dzonatas suggested so many times here, to turn off the journey steps and when i did it i could finally play.
2 minor details that will fix your game and won’t ruin your game play.
1st. Try to open an area before you start engagement. At the time you firstly open a new area you’ll suffer a great lag.
2nd. Try to avoid fights in bridges, you’ll lag the hell of it and probably you’ll find your self dead from great fall.
I do agree, trust me, it’s difficult, but still you can do impossible things even in this state 
.