Have you noticed any SharePoint pages in your environment that load slower than the others? Want to know why? The SharePoint Developer Dashboard can provide the answer. Its name makes it sound like it’s only for developers. However, it's an extremely useful tool for IT professionals as well as SharePoint site owners.
The Developer Dashboard shows you how a SharePoint page is performing. This utility can help if a page is loading up too slow, a Web Part isn't working well on the page, or even if a database query on the page is slowing the whole page down. It shows all that information and more--directly on the page you're viewing.
The video below shows how to enable Developer Dashboard on a SharePoint web server (this step requires permission to the web server) and how site owners can monitor page performance.