I have an issue that has plagued my New vegas for ages and no one has known how to fix it. My FPS is at a rock solid 60 when I load my save but, after 10-15 mins of gameplay I start to notice it slowing down, after 40 mins it is as low as 35fps which is unplayable to me. When I exit the game and load it up again it's back at 60FPS again. I had heard it was a DoF related issue but I have disabled any DoF mods and disabled it in the game settings, If anyone can provide any help it would be much appreciated, even if just suggesting which type of mods could cause this, Thank you.