I just remembered something. Wasn't Fallout 3 not originally released on PS3? I believe Bethesda had to work to make it more compatible, hence why F3 (without any add-ons) ran so smooth compared to New Vegas and Skyrim, despite being on the same engine. It seems that if they had taken effort to make the coding more compatible, like they did with Fallout 3 (Initially. Seems they got lazy with the Goty edition and everything after), this wouldn't be happening.