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:
To disable the Developer Dashboard:
STSADM.exe –o setproperty –pn developer-dashboard –pv Off
Then enable the Developer Dashboard with OnDemand Switch :
STSADM.exe –o setproperty –pn developer-dashboard –pv [ OnDemand | On | Off ]
‘OnDemand’ turns the Dashboard on, but hides it until the click of an icon beside the ‘Open Menu’ on the top of the SharePoint page.
Very cool stuff!