Really low FPS with I44 mod

INVASION 44 MOD PROBLEMS.

I get terrible framerate when I play the invasion coop mission. Like in the single digits. I have tried all resolution combos, changing all the graphical settings nothing seems to work. The best I can get is ~15 +/- 4 FPS when I am on the beach. I basically makes the game damn near unplayable.

This is running on Vista 64 system (IT WORKS WELL FOR REG. ARMA) Q6600, 8 GB DDR2, GTX 285 OC 1GB. Hopefully someone can help me out.