So, I did a test, here's how it was.
With buffered rendering, at 2x the resolution and 2x textures.
The opening movie was at 30 fps all the time, the movie after selecting new game also ran at 30s,
with some random drops to 25 and going up to 30 immediately.
Then things went to s*** in battle, with 14 to 17 fps.
With 2x resolution and texture upscaling off, I got the same in movies and 16 to 18 fps in battle.
With 1x resolution and texture upscaling off, I got 20 fps in battle.
Finally, with non buffered rendering, I got 20 fps in battle.
The main menus and misc. were at 30 fps with every setting.