As somebody said it is a tweak. It's about increasing cache size, so increasing amount of memory the game will use. You will have more data in RAM and data transfer from RAM is much faster than from a hard disk. So instead of taking data from HD the game will take it from RAM, if of course needed data was preloded there. It may speed up the game in some situations.
rZor you may try increasing your cache size from 64 to 256.