I know that is not a big issue for the creator who's worked on this update, but it is a very big one for the user. We tried to keep using Acrobat XI the longer as possible, but we had to go in DC, the visual is discutable, but the issue with Output Preview (page rendering, flickering, slow appearance) this is unacceptable!! For a person who's verify many thousand pages per day, it's very frustrating. As an important company as Adobe, this is a lack of respect for the customer, I'm very disapointed.