As for your settings.... Options-> Graphics/Video-> Advanced->
HDR (turn it off), AA and AF (off), reflections (recommended setting with star)
Shadows (low). Don't get too low on the res or accurate sniping will be impossible.
Theses setting should help. If you need it better than that there is a way
to make the game run on DX7 or DX8 to get more fps but I can't remember how.
your best fps will be the dx of your video card if u know that... also u could try mat_picmip 2 not sure if it works anymore (used to be 4 til valve made a retarded "stop the cheaters" update) that command wont work on sv_pure 1 servers tho
theres also a bunch of other things that could help like disabling dead bodies, blood splatter, etc if u must to play u should. If u need to know the commands for this u can pm me or just ask in here ill be more than happy to help u get decent fps.