Game tweak, anyone?

[Lololopoulos]

Hello fellow flyers,
I've been flying IL2 for some years but I'm still a newbie at computer. After the latest official patch, I still only get about 25 fps (no visible improvement from US release) with everything set on low and all the options unchecked. And 10fps is common with some of the options set to high.
So my question is, what r some of the common reasons that cause the low fps (both game and computer)? I heard there r many ways I can tweak my computer to make it perform better but can you guys please give me some directions as what to search for? Maybe some helpful websites I can read?
My specs r in my sig.
Any advice is welcome.
Thanks in advance!!