I did VCAP5-DCA just this week in a Central London VUE center and parts of the lab were pretty grim and frustrating to work with (e.g. laggy and slow on the screen refresh). You would expect a central London testing centre to have pretty quick connectivity but it felt laggy to me. I did the VCAP4-DCA in the same test centre and that was much better.
This time, though, they had new wide screens which was nice!
Just for the record I am not putting any potential pass/failure down to the good/bad performance of the lab 