I'm going to quote what developers told slightly, I'm not going to read out the entire statements because I don't want to get them into trouble, so I was told that Ubisoft engineers that Watch Dogs Legion is slightly better optimised on the Series X than Assassin's Creed Valhala, Ubisoft Toronto were actually the first Ubisoft studio to actually receive Xbox development kits, but Ubisoft Montreal got the development kits in November of last year which is not terrible but of course they were definitely not final...speaking with the developers, up until July (ish) of this year Ubisoft were actually targeting 30 FPS on ALL console versions of the game, but they decided to up the frame-rate to 60 FPS...those targets were not updated as aggressively as they should have been given the 60 FPS nature"
"I do want to discuss the Series X and the tools situation because it's kinda become a meme at this point, and to my understanding speaking to 2 developers, one of which is more well tied into Playstation side of things who has given me a ton of information in the past which has been accurate, so I'm going to give them the benefit of the doubt when they tell me this, they have said that Series X tool chain was perhaps not as advanced as Ubisoft would have wanted early on, although the tools are a lot better now, they were not as robust in the early bring up"
There were also issues with the drivers of the Series X GPU which actually lead to delays in mass production. I recommend watching the whole video.
Why is Assassin's Creed Valhala running better on Playstation 5?
"It seems that given the short time, it was easier to optimise on the Playstation 5 hardware these changes (from 30 to 60 FPS), I was told that Sony's profiling tools are a little more consistent and more advanced than Xbox... Sony's tools are a little more consistent compared to the previous generation".
"I think the Series X will improve as developers get more familiar with the hardware and the actual tools themselves improve, thats not to say the Playstation hardware is going to remain stagnant either, the tool change for the Playstation is going to continue to improve, Sony have teams like the ICE team who will do their dammest to improve the performance of the PS5 hardware".
Some other nuggets about the Playstation 5
"It's kinda like the PS4 and the PS3 architecture and had a baby which is the PS5, you've got the ease of the development of the PS4 and the depth of the PS3".
"I will also in the next day or two, put out a video because I actually learnt a lot more about the PS5 and the Series X which have not been detailed especially about the PS5...I now have a good understanding of what the DDR4 memory is and how much CPU allocation there is for the PS5, I'm just doing a couple of checks with the developers before I put out the video".