In the ancient past, Liferay had a feature to discover individual portlet's rendering times. It looks like this got lost with the move to OSGi -  but it's also reasonably simple to replace. Especially when it's for portlets only (fragments are still on the to-do list)

Some portlets take longer than others. While that's ok - they typically provide more value and dynamic content - you might want to limit their use to the less frequented page and not have them on your most public landing page.

Here's a quick proof-of-concept that you can use to display each individual widget's rendering time. It's also a sample for introducing a PortletFilter to each and every existing portlet in the system.

Let me know if you find it useful, discover bugs, or have extensions that you'd like to see in there.