The first thing to do is to check your Software Assurance and upgrade to the latest edition, for free if it is still active.
It would appear you are asking for too much data from your Exchange Server. This can occur when your calendar recurring appointments have no end date in either the source or destination side. The "no end date" of a recurring appointment defaults to AD 4501, which is +2500 years in the future, so a few daily appointments are extracted to thousands and thousands of individual appointments in order to be precise and exact in replication. Usually this is not needed and on one client, the appointments added up to 9 million instances until the data was repaired.
You can use the Add2Outlook Toolkit change items option to fix invalid recurring appointment end dates on both source and destination sides of the relationship, with the Add2Outlook Toolkit. This routine will edit and change the end dates of recurring appointments for an entire folder to 5 or 10 years in the future, for example and use a group policy to require an end date moving forward so it doesn't happen again. See this link for a better description. For the Add2Outlook Toolkit, this is the link and this is the link for us to fix it for you though Premier Remote Support.
Also, if you have many relationships, (+250) combined with the above solution, we have noticed you can change the method it uses to load relationships and sync by changing the registry key for Session Sync Pass in the HKLM Software or Wow6432 Node\Software\OpenDoor Software\Add2Exchange\ to 2 instead of 3 for a full sync.