I just had a similar problem when trying to load a save that was made in any exterior area or when transitioning from an interior or exterior area. In my case it was something in the enb files after upgrading Vivid Weathers. Not sure what I borked up but wiping them all and rebuilding them from the guide fixed my CTD. I am however now facing a severe FPS drop. I went from 50s to 30s around Whiterun stable. Edit: It looks like my FPS issue near Whiterun was caused by Elysium Estate. As soon as I dropped that mod my FPS is back to normal.