Zimbra Server 5.0.9 and Zimbra Connector for iSync 5.0.2201

We have a special executive person here, that has >4500 calendar entries on his Zimbra server account. Syncronisation via Connector 5.0.2201 over iSync is crashing after approx. 1800 entries.

As reason why the process ZimbraHelper.app crashes I found out that the process took more than 2GB physical memory (RAM). I assume, that a process on Mac OS-X 10.5.4 cannot take more than 2GB RAM (even thogh more would be available).

What I don't understand is, why ZimbraHelper.app absorbs that much RAM. I understand that synchronising 4500 appointments is requiring a lot of ressources, but it seems to me that it's not possible to do that with the SOAP interface.

I'd be glad for comments to this scenario.

Thank you in advance
- Dan

PS: Please don't give me the advise to switch to CalDAV. I will post a separate problem description when I try to use CalDAV.