The CPU usage GSdx reports at the opening scene is ~25%? Then it's not your graphics card...
Try using some speedhacks. Also go in advanced and hit default and then ok
FFX, as well as Budokai 3, even with all speed hacks activated, don't go at more than 50% of total fps.
I turned the iso to ntsc using a program, hoping to obtain more speed, but it didn't help me.
Maybe is my notebook that can't stand it, or maybe can I do something to resolve this problem?