There is no any particular limits. Could you clarify a bit: are you connecting from EPiServer CMS to the SharePoint server over Virtual Path Provider for SharPoint or files are synced between SharePoint and EPiServer CMS over Content channel? In case of synchronization over Content channel you might face with request timeout on initial synchronization if you have a lot of big files. In order to see what is going on the SharePoint side you can configure logging as its described here.
It's configured to be used as a VPP.
Could it be that the list in SharePoint uses pagination with 100 items a page? According to the customer/end user that matches the number of files that are synchronized.
I have found where the problem is. The SharePoint web services API has a default paging behaviour and VPP for SharePoint uses the default settings, as a result users can see only the first "page". I have created a bug for that issue (bug #72700). If you need a hotfix, please contact EPiServer support.
Thank you, no more work for me then = )
In this case, our customer will rebuild their lists in SharePoint to get an better overview (and to solve this bug).