Keep contents of header and footer regions consistent

You may be able to improve performance by keeping the contents of header and footer regions consistent across page layouts to prevent unnecessary downloading and re-rendering of these regions during each user page navigation.

You should consider expanding this approach to other page layouts that have similar content. For example, when a page loads, if any region remains the same (if it contains exactly the same widget instances), from the previous page, it will not be reloaded. For more information, see Understand widgets.