Something wrong with my graphics card?

[Zakkk8]

I've had Call of Duty 4 and a Unibody Macbook Pro - 4gb RAM, 9600 Nvidia 512mb, 2.53 ghz (doesn't have snow leopard) - for about a year now. I stopped playing COD4 for about two months, and just started again this September. There's one thing that's really bugging me: It seems to be running a lot slower. Earlier when I had this computer it ran at 30-50 fps with all graphics options on maximum except shadows, anti aliasing, and smoke effects. Now, it seems to peak at 30 fps and usually ends up around the high teens low twenties range, and when there's a lot of action it can dip down to 10 fps. And, this is with some options -like dynamic lighting and textures- turned down. The reason I believe this might have something to do with the graphics card is that when I change it to the 9400 integrated one the framerate stays the same, when earlier it would be almost cut in half. Does anyone have an idea what might be going on? I know some people are having memory leak issues with Snow Leopard and this game, but I don't have Snow Leopard. Thanks in advance.