Hello! I have done some work on minimizing the number of requests sent during a WebDAV and/or CalDAV sync. One major improvement is the use of CTag (https://trac.calendarserver.org/browser/CalendarServer/trunk/doc/Extensio...), an extensions supported by Google, Yahoo and Apple calendar servers. The other improvements is a change of the tradeoff between memory and speed in favor of speed. Result is in the webdav-optimization branch. Only problem: in contrast to my expectation (see comment in one of the commits), having the UID for each CalDAV resource is relevant. Without it, the mapping between existing items and new items with the same UID fails. Found when running the Client::Source tests. So now I'm back to the drawing board. Expect some update on Friday. In the meantime, can someone review the commits - Salvatore? -- Best Regards, Patrick Ohly The content of this message is my personal opinion only and although I am an employee of Intel, the statements I make here in no way represent Intel's position on the issue, nor am I authorized to speak on behalf of Intel on this matter.