Originally created by Google and called Google Sitemaps, the XML sitemaps protocol defines the <priority></priority> tag. This can be used by webmasters to help search engines determine which pages are most important.
What you may need is a caching product in order to lessen processing requirements, such as querying the database on every request. One of these caches is the Open Source product, OSCache. It may not be the best solution in all cases but, as a maintainer o