I've heard that too. And also Xbox had 2 different DirectX APIs, one more customised to the console, and one that's the standard Windows DirectX which is not as performant. From what I've heard most devs used the latter as it made porting the PC version of the game easier, and sales on Xbox would be tiny compared to PlayStation (1/3rd the install base, sales even less than that due to Xbox users not buying games and just using gamepass) there was less incentive to optimise.
