I have somewhat similar computer specs, and trust me; it won't get much better. You can tinker with the emulator as much as you want, try different settings, switch between plugins, but I doubt it'll do anything to improve the speed. If you do things right, some things will work at great speed, while scenes with a lot of characters or large area's will run slow to sluggish. I've been playing Super Paper Mario, and a lot of the game plays at a decent speed... unfortunately, boss battles don't fair too well and might cause the FPS to go down to 20-30.
I hope to get a job eventually and buy a computer that will be able to handle the emulator... but what I have now, I'm happy that I'm even able to play most of it at a good speed.
I hope to get a job eventually and buy a computer that will be able to handle the emulator... but what I have now, I'm happy that I'm even able to play most of it at a good speed.