Why FPS should I be getting with Skyward Sword?

Okay so here is my specs first:

I7 3770K - 3.9 GHZ
GTx 670 Video Card
32 GB of DDR3 RAM

Dolphin Settings:
I have Directx 11 Set
Auto Internal Resolution
True Resoultion at: 1920X1080P
AA At 8X
Antitrophic at 16X

I average 25 FPS, and go as low as 15

Should I be getting more or do i have settings wrong?