When I sync my calendar in my Samsung Galaxy S5 through Kies 3 with Outlook, why does it take hours?

[AC Question]

When I sycnronise my calendar in my Samsung Galaxy S5 through Kies 3 with Outlook it takes hours.

I am only trying to sync the calendar not all the different options. I select the appropriate folder to sync rather than 'all' and whilst the progress bar eventually gets to 100% the process never completes. Any ideas?