I played about 30 hours on the Pro. Then I upgraded my PC and played it there installed to an SSD. The difference is incredible. There are literally 1-2 second load times now, I can't even read the loading hints. On my pro it was like 30 seconds at times.
It really does change the dynamic of the game as you never wait.
I did the same thing. The first time I loaded a quest and it was ready instantly I was like "There must be some mistake."