world of warcraft on macbook osx 10.6.8

i play world of warcraft often on my macbook. when i already have it set with the lowest graphics and even so when i get into a group with more then 10 people i get all laggy and even when when im in a non crowded area in wow if i press the volume button the animation from that makes wow lag out.

anyone know of anything i could maybe upgrade on here that will fix my problem?

here's my macbook stats...

HARDWARE

Model Name: MacBook

Model Identifier: MacBook4,1

Processor Name: Intel Core 2 Duo

Processor Speed: 2.4 GHz

Number Of Processors: 1

Total Number Of Cores: 2

L2 Cache: 3 MB

Memory: 4 GB

Bus Speed: 800 MHz

Boot ROM Version: MB41.00C1.B00

SMC Version (system): 1.31f1

Serial Number (system): W884104H0P6

Hardware UUID: 52509E87-990A-5FA9-9EEF-B3E765EDED2D

Sudden Motion Sensor:

State: Enable

GRAPHICS

Intel GMA X3100:

Chipset Model: GMA X3100

Type: GPU

Bus: Built-In

VRAM (Total): 144 MB

Vendor: Intel (0x8086)

Device ID: 0x2a02

Revision ID: 0x0003