If you are having audio problems, I would suggest using rev3950. Metroid Prime sound seemed to be perfect throughout the whole game with that rev. And frankly, that rev seems to be the fastest for games like Prime, Wind Waker, Twilight Princess, Mario Galaxy and others.
However, if you use that rev, then you would have to switch back to OpenGL for graphics. It's just a matter of trade-offs, though, if you want the good sound that the rev had.
And also set frame-skip to 2 or 3 under emulation settings to speed it up a bit.
Lastly, EFB needs to be set to RAM and Safe Texture Cache on for the scanner.
Combination of finding the right rev and the right settings makes most games playable even on crappy systems like mine.
However, if you use that rev, then you would have to switch back to OpenGL for graphics. It's just a matter of trade-offs, though, if you want the good sound that the rev had.
And also set frame-skip to 2 or 3 under emulation settings to speed it up a bit.
Lastly, EFB needs to be set to RAM and Safe Texture Cache on for the scanner.
Combination of finding the right rev and the right settings makes most games playable even on crappy systems like mine.