I having been playing around with a new SharePoint 2010 feature called the Developer Dashboard. It is a great tool to use when figuring out how your pages work behind the scenes.
See some previous postings on the topic here: http://blogs.technet.com/b/speschka/archive/2009/10/28/using-the-developer-dashboard-in-sharepoint-2010.aspx http://powerpivotgeek.com/2010/05/18/enabling-the-sharepoint-developer-dashboard/
To disable the Developer Dashboard:
STSADM.exe –o setproperty –pn [...]