Alright, so I used to play this mod when I still had my old GPU, which was smaller than half a chocolate bar, so I wasn't surprised about it. Now that I have one that can run the base game at full settings (even using the command to fix shadow lag, which I heard can lower your framerate) without any issues. It runs perfectly smooth, even in vast areas like the dam.

In this mod however, there are a few places that SEVERELY impact the framerate, bringing it down to about 40 or lower (I don't know the exact numbers) for seemingly no reason.

Some of these places are:
-The office/cafeteria area (where the track "Year of Death" is played).
-The room where the ambush takes place.
-The surface areas.

It doesn't use any of the new graphical features (dynamic lights/shadows, god rays etc.), so I have no idea why these particular areas are so laggy. Perhaps there are too many objects? something with the scripted events? I don't know!

I hope there will be an update for this mod that fixes these problems.