How to identify if wcm item is causing performance issue
1.If unclear which content item is at fault, focus on one page that demonstrates a performance issue with the fewest WCM Rendering Portlets
2.Identify the wcm content rendered in the WCM Rendering Portlets on the page via Edit Shared Settings for each Portlet. For V8 and above, you will need to set the page into Edit mode to see the drop-down for Edit Shared Settings in the upper right hand corner of the portlet. Another option is to navigate to the page under Administration > Manage Pages > click icon to "Edit Page Layout" > click drop-down for the WCM Rendering Portlet in question > Edit Shared Settings
3.For Portal V7 and below, clear the WCM Caches using the Support Tools Portlet* > Launch Utility JSPs > Clear Cache > Clear Caches. For Portal V8 and above, run task: action-wcm-clear-cache-all. Note that clearing wcm caches can have a major temporary impact on server performance while the caches are re-populated. Use with caution.
4.Clear the browser cache as well
5.Preview each WCM item from step 2, using the preview option in the WCM Authoring Portlet
6.Preview each item a second time without clearing the browser cache and WCM Caches
Any wcm item that takes longer than 5 seconds to render is suspect. Check the presentation template mapped to that content's site area. Back up the contents of the presentation template then delete entries in the presentation template one at a time and re-preview the content until the component/element causing the performance issue is isolated.
*Note the Support Tools Portlet can be downloaded here: