I saw this setting called Inferno & NP9660 Use ISO Cache option in my 6.60 PRO-B10's recovery menu. I want to know what it does and the options under it (Cache Size, Cache Number, Cache Policy). What happens when I disable it?
The ISO cache does the same thing that the UMD cache in stock firmware does: saves frequently used blocks of the game disc in RAM to improve load times. The UMD cache only applies when playing from a physical disc, and the ISO cache only applies when playing from a disc image on the memory stick.
The settings under it are for fine-tuning; Cache Size is the amount of memory the cache is allowed to use, and Cache Policy is the algorithm it uses to decide which blocks to cache. Cache Number doesn't appear to be documented anywhere, and I have no idea what it does.
Note that running your games from the memory stick instead of from the UMD already gives such a huge improvement in load times that the additional improvement from using the cache will be pretty small.