ATI Radeon HD 4670 1 Gigabyte w/ FPS Drops

So I was running an NVIDIA GT 520 2 Gigabyte and it was just not good enough to run the game. Today I got an ATI Radeon HD 4670 1 Gigabyte from a friend, and decided to give it a go. It runs much smoother, but I'm noticing major FPS drops when I go to cast certain spells (mainly fireball). It literally makes the game unplayable in groups due to all the animations. Anyone have this issue or know of a fix?

BTW, my 520 GT scored a 210 on FurMark's 720 benchmark test, and this ATI card scored a 680. It isn't too terribly better, but if it can run BF2 and COD BO2, it should be able to run this :(

EDIT: I assume it has something to do with loading the textures/animations or whatever into the VRam due to the specifics of the issue. I'm running a 3.2 GHZ intel dual core, evga 680i sli board, and a 3xx read/write SSD.