Getting there three hours before the first display is a bit extreme, There is not enough to look at to last the near three hours for the first display - unless you want to go on the funfair.
It is not unreasonable to think that aiming to arrive 45 minutes before displays commencing would be enough - to park up and take a leisurely stroll round.
But thats neither here nor there - the real point is the traffic problem and lack of redress from the situation last year. Taking 1hr45 to do five miles is poor by anbodys standards.