Major FPS Drop

[Blainy]

Since the last update my fps has dropped from 30-40 to 10-15 on average. I have it on medium settings.

I dropped the settings to low and the fps only increased by 5.

I have a fairly outdated computer which should probably cause the fps to be at 15 fps but I'm just confused that its dropped since the recent update.

Windows Vista Home Premium 64 Bit
Intel Core 2 Duo CPU T8100 2.10GHz
4GB RAM
nVidia GeForce 9600M GS

All drivers updated.

Unfortunately I can't seem to find anything that's compatible with upgrading my computer and I won't have enough for a more decent PC for quite a while.

Can someone tell me if they've had similar problems and if they've found a solution? Or any ways to increase my FPS in general.

Thanks in advance