I started again (as i missed a load of artifacts at the start so ive discovered lol) with my new settings and it still dropped in the same places, so it can't be that, i did notice however, that if you go into the settings menu and drop the textures to medium, then put them back to high, the stutter disappears, as i was testing while spinning the camera around Lara, when it got to a certain point the frame-rate plummeted, then when it moved away from that point it shot back up again, so i dropped the textures to medium, put them back up to high again, then started spinning the camera around her again, and this time it was perfect, so god knows.