Well they released an update to DW9 today which allows you to switch from movie mode which is default to action mode which lowers the graphics but seems to have fixed the pop in issues it was having and general performance on the PS4. Gave it a try and performance is much better so seems like it was a case of just couldn't handle all the stuff it needed to generate at a time. Still got some bugs though... like summoning my horse only for it to spawn in the ground beneath me and get stuck in a swimming animation and siege battles are still pointless as whats the point of siege weaponry when you give all characters a grappling hook that lets them climb any wall you can just punch the castle officers in the face to capture it. Kind of rendering part of your game obsolete there.
Oh well with the performance now fixed the game is in a playable state now so going to at least complete the stories for my remaining few characters with Sima Yi, Lu Lingqi, Zhang Liao and Guan Yu down with Zhen Ji, Yue Ying, Sun Shang Xiang, Zhang Chanhua, Pang Tong and Gan Ning still to go.