GT5 Has 3 Loading systems.
- Perminant installed data with extra installs of commonly used data as it goes. After all the commonly used data is installed you wont see installing text untill you go to a uncommon event it then uses.........
- Tempary installed swap disk data per session.
- BD only data.
With perminant data the game only loads that data from the HDD.
With Tempary installed swap disk data, it installs the data needed to the HDD for the races and Menus, per session, This means the BD is not used during the RACE.
IF you don't pre install the PS3 has to install All the race data in to the swap HDD storage area, This takes longer per race loading, With tempary data storage, the BD is not accessed during the hole race.
If you don't pre install and don't allow the swap disk function as you turned them off in options, only basic & patch data is installed on HDD and the BD is used constantly on menus and is perminantly active during races.
People who do online alot want BD access combined with HDD patch data as its faster (online is not on the BD after all). If you pre install the BD is not used as much and the HDD has to load all the Patch and normal race data buy itself.
Because there has been so much extra data patched, the performance of HDD loading all of it has passed a point where BD+HDD loading is now faster on SOME systems. Slims BD drive has got cheaper more nosie and slower access time as more models get released.