The game only displays the ship movements that are in its current view.well, will this make the time shorter or will it take just as long but you just don't see them moving anymore?
It does speed things up - but not to "zero-time". Depends how many individual ships or fleets have to move, their speed (i.e. how many parsecs they have to be moved), and your system. Once you get into the thousands with speeds of 25+, then turns can still take quite a while to process.
Fleet them wherever possible, as that reduces the number of units that have to move.