Off - Disables experimental frame-flipping detection code [default]
On - Enables experimental frame-flipping detection code - fixes Final Fantasy games, may cause problems in others
This is an experimental method (i.e.. it may or may not work) of detecting the time at which the PSX application switches between ('flips') using the frontbuffer (the graphics that are displayed on the screen) and the backbuffer (the area where graphics are drawn to, in preparation to be displayed on the next 'flip' of buffers).
I had to make some modifications to the code that detects a 'flip' between buffers (non-trivial in a hardware GPU!!) so that the battle-menus in Final Fantasy games worked properly, and since I wasn't sure whether it would mess up other games, I made it a selectable option. So, if it messes up a games, you can disable it for that game.
RECOMMEND: Off (On for Final Fantasy games)