Weird fps issue

Hello all,I was flying the lds 767 today and just after an uninstall and re-install of ge proII the frames would behave strange. Normally I get 35 fps locked at 35, but now the frames drop to 19 when im looking out of the window of the aircraft at the airport (runways, taxiways, and the building itself.) Once I look at the overhead or look down so the windscreen in not insight the fps return to a silky 35. I ran filemon and observed that the pc would access a bunch of textures and some ultimate terrain files and other various fs things when the fps drop occurs. Any ideas on whats causing this, gosh im so sick of these bizarre problems.