Performance problems after combat?

[preifx]

Doom3 has lower FPS than Penumbra on my computer, I played doom3 with a low graphic detail...but in penumbra, I can turn on 2x FSAA & 2x anisotropy at 1024x768, no motion blur(I don't like it), no bloom(the picture is not so correct), without the "dogs", it runs well.