This was causing the game to output thousands of FPS during the loading screen when it would run uncapped if Immediately Present XFB was enabled.
Please see Redmine 13447 for reference.
This is another one of those games that has an optional screenshot
feature where the images end up all black if you have Store EFB Copies
to Texture Only turned on. Like for other such games, let's not force
Store EFB Copies to Texture Only off, since it's a large performance
impact for a feature most players won't use.
There's one wrinkle here. As part of teaching the player how to take
screenshots, the game forces the player to take a screenshot before it
lets them progress in the story. However, the game doesn't care what's
in the screenshot, so you can progress just fine even if Store EFB
Copies to Texture Only is turned on. I personally tested it.
For buttons and some character icons the game loads palleted PNGs and
tiles the pallet indices directly into C4 textures but fails to take
into account that PNG and C4 use opposite nibble orders. This causes
adjacent pixel columns to be swapped, see issue 13370.
Also disable Immediate XFB for the Japanese release. It has the same
black screen and flickering issues as the other regions.