Recently I was working on a dynamic Fetch XML query that was adding a lot of conditions. During a batch run the CRM Service started to crash when the xml size got around ~135kb. My first thought was that there were a size limit of the SOAP message that we'd cross, but after further testing it would become evident that fetch queries has a limit of 2097 <condition> elements. That is 2097 per <filer> element. If a query has linked entities that has 0-2097 conditions then the main entity can have a maximum of 2095 conditions.