how to improve speed of LoZ Wind Waker in Dolphin

i'm new to dolphin emulation, and i am trying to playing Legend of Zelda Wind waker on dolphin. i realize my specs are probably lower than the recommended specs for dolphin, but LoZ still is playable, although somewhat choppy (15-23 fps outdoors, 25-30 in dungeons, indoors, etc). So please, I need your help adjusting the settings to play at full fps. here are specs:

CPU: Intel Pentium Dual Core @3.00GHz
Graphics Card: NVIDIA GeForce GT 520
RAM: 2GB
Windows 7 32Bit

Dolphin 4.0.2 (at default settings).

i don't intend to play any other games on dolphin, so any changes which can break other games are acceptable.

thanks.