Well, it was originally a PS3 game. I would just assume that the loading system was ported from the PS3 and did not take advantage of the better HDD (vs. disc) and maybe better decompression performance. E.g. I would assume that there was still code in it that worked good on the cell CPU but not that good on jaguar cores.
Loading times were never important for porting games. More or less one time loading times at least. So the 1:30 was good enough to release the game.
Btw, I never understood why games load so long to reach the main menu of a game. Yes they might preload some stuff, but really don't makes much sense if they have still long loading time when starting a new game or loading a save state.
Just like the "press a button" to enter the main menu or only to proceed to the next loading screen before the main menu (e.g. if I remember correctly FF XV and witcher 3 do that).