Outlook synchronisation sloooooowwww

Hi all, Just set up the Outlook synchronisation in a live environment. Works without any errors, and online sync is very good. But, the salesperson who has to exchange his data from Outlook with Navision every night will get annoyed: the synchronisation takes about 10 minutes(!!!) for about 2.100 contacts, and no changes werde made at all! I noticed that most of this time is consumed by importing contacts from Outlook. That is what I do not understand. If there aren’t any changes in contacts on the Outlook side (and in my test scenario, nor are there on the Navision side), why then do a full import of all those contacts? Does anyone know what exactly is synchronized in the different (7) steps?