New Mario Bros Slow 20 FPS

[heberreis]

Cpu - E6600 2.4 Ghz, 4GB RAM , HD 500GB SATA2 , Video - ATI HD4850

System - Vista Ultimate 32Bits

Dolphin r4635

Game New Super Mario Bros .

Graphics of the game - good
Sound of the game - good
When the game start on Stage 1, the FPS down 60 FPS for 20 FPS.
how make to resolve the problem of the FPS ?

how make to accelerator FPS of the game ?

Thanks for peatetion .

Heber Reis