[Zope] When is access.log written?

Can someone please clarify for me.. At what exact stage during accepting and responding to an HTTP request does ZOPE write to it's access.log? When the request is initially received and before it is processed? When ZOPE has finished creating the response and serves the completed page out? I'm trying to determine if apparently poor server performance is caused by a slow web proxy on our network. -- Eddie Butcher Road Tech Computer Systems Ltd. http://www.roadrunner.uk.com 01923 338033