WoW Weather EffectsFollow

I've got a newish computer - made in October - Radeon 9550 card which I just updated the drivers to, gig of ram, more free space on the hard drive then I know what to do with, etc... I run the game at medium settings, usually, and have no problems.

Except for weather. I've got the effects turned down all the way and the "uncheck if it crashes your computer" checked and unchecked... and weather lags me to no end. I'll touch a key to turn slightly and end up turned all the way around. I can't move well and everything is jerky and my framerate drops to about 12-19, depending where I am.

Any specifics on what I need to alter or what I should be upgrading to make this work better? I assume RAM is the simplest solution, but since I'm kind of computer stupid, I thought I'd ask here before I spent the money I'm supposed to be saving for school. >.>