Internal/exterior sub view fps problems

[Kataki]

After spending a few hours trying to get my copy of SHIV to work correctly I am still having problems getting a stable FPS.

My computer specs:
AMD Athlon 64 3000+
1.5GB system ram
Nvida geforce 6600GT
DirectX 9.0C
Realtek AC'97 audio

Now before you say my computer is **** etc I have had the game running smoothly before (last night after a few hours of reading forums/messing with setting it was running at 15-20+fps outside on the open ocean even when viewing ownship, 30 fps in the sub most of the time except when I looked at the navigator) but when I went to run the game this morning it is back to running like ****.

My FPS outside, while not looking at my sub. is usually in the range of 10-20 fps (which is fine for me)around 60-90 while looking at the map, but the moment I look at my sub it starts to stutter to about 7-9 and when I am inside the sub is slows even farther to 2-4 fps. Since most of the game is played in and around the sub this pretty much ruins the game for me.

I have enabled VSYNC in the cfg files and made sure the refresh rate is that of my monitor (75hz)

my cfg:

[VIDEO]
Resolution=1024,768,75,22
DynamicShadows=No
FullScreen=Yes
Synchronized=Yes
TextureResolutionHigh=Yes

Can anyone explain why my FPS would be so low around my sub?

Edit:
Erm sorry didnt even think to post this IN the techinical help topic.. even though I read it DOH!

[AVGWarhawk]

What option do you have checked in the game? These saved my FPS:

EE: off (for now, fog killed my FPS)
3D water: off, I liked the wake option better anyway
Glare: off
Sunlight under water or sunlight rays: off

Everything else checked. Reduce some of the particle density. See if these help your ills.

[Kataki]

I should have been more clear, I have tried lowering the settings to the lowest possible and while I do get a significant boost in FPS outside the command room, and external view while not viewing my sub, I still only get 3-4 fps while in the command room.

[Kataki]

^bump, problem kinda solved.

Hmm after a bit more testing it seems the "texture quality high" only takes affect after completely restarting the game, more over it seems that my CPU is indeed the choke point (the textures seem to cause EXTREME slow down around subs but not for ships 0_o)

My next question.. is there a way one could mod the game to use high quality textues for ships but not subs?