I was in Porec last year middle of june and it definitely wasn't noisy , in fact it was very quiet . I'd imagine that it would be much busier later in the year but don't think its the kind of place to get very noisy ,, more restaurants than bars .

Last summer Biblos was opened in Porec- the biggest disco club in Croatia, (but it's far from the centre of the town, on the hill) so more and more young people are coming every year. Every summer there's 5-8% more turists in Porec but it's still ok for families with children so I don't think you would have any problems. When I was a kid I very much enjoyed vacations in Porec with my parents. It's best to stay in villas or apartments in quiet areas between the wood and the beach...