Dynamic Lighting at night issue

Hi all. So I noticed last night that every time I load up a flight at night especially at airports like YYZ or BOS, I get a huge drop in FPS and everything just pans around slow. Not sure what the cause maybe. I recently purchased a new Acer monitor so everything runs butter smooth up until I arrive at an airport like YYZ or BOS . Both installed from FlyTampa. Ran a quick test at daytime and everything runs ok there. Only at night is where I find the issue with FPS. I did research and lowered my AA down to 8xMSAA, even tried with 4x and 2x. Still doing the same. Come to realize is that when I shut off dynamic lighting in game settings, it seemed to have fixed the issue. Although now by doing that it makes lighting look blah and disgusting without dynamic lighting on. So is there another tweak or configuration to solve this issue? Or do I just have to wait for a new update to fix the problem?