Outlook 2013 hangs and wait to update folders

Hi Experts,

not on all bit on some client machines I have an issue with outlook.
With one employee it is really annoying because when he is not using outlook for 15 minutes , then later it stuck for 30 seconds.
The message is always ...waiting to update the folders...

The client outlook version is 2013 and the exchange server version is 2007.

Can you help me to find the problem ?
I am sitting on the same floor but I haven´t this issue.