Sounds like you haven't come upon the rerecording version. GBA emulators tend to have that kind of problem, I've noticed. And even using the most recent one, I still have issues on it. It's probably mainly a problem in your computer's processing capabilities, but that's not exactly the only possible culprit complicating things.
Also, put video:1x. It makes the screen of the game, but the graphic and emulation are perfect and almost identical to this game played in a GBA. ... At least for me it works.