Consider that most of them are due to (VERY) badly organized data for each module (there should be 4, if memory doesn't fail me). For example, in the in-game menu there are over 100kb used for NPC compressed gfx, which are completely unused.

The other problem is seek time, since data is scattered all over the CD, without a decent method to glue them together when they are needed, so the game jumps a lot through the disc, making everything slower to load. >_>