For one, they should disable the Quality mode for the split screen and just go with Performance. I mean, we've initially selected Performance in the first place, but apparently the game defaults to Quality immediately when you enter split screen (which is ridiculous). And since the game freezes more frequently as you progress, this insinuates some kind of memory leak, unoptimized scripting or stacking conditions (I'm comparing these problems to Skyrim, but it may not be the same thing).
The problem isn't graphical so either quality/performance doesn't make a difference. It's an optimization issue and the ps5 processor can't handle it.
Edit: There's a comment on the Digital Foundry video talking about the freezes and I recommend everyone where to give a like to it, maybe they see it and decide to test it further.
Good spot re the comment on the DF video. Still unbelievable that DF didn't acknowledge the freezing issue even once. It's like they've all be paid by Larian to keep quiet. The longer they remain silent about this the more I'm losing appreciation for them as a developer. So sad, they used to feel like the white Knights of the modern gaming world...now it feels like they will let their success turn them into the next blizzard.
