Recently I was developing a new site for a client that had exceptionally high processor usage for every page load.  Now I have other Drupal sites on this server that use a similar module setup but use a lot less processor.  My interest was piqued.

I just ran across a bug in Drupal that was drastically affecting my XML Sitemap listings.  The bug made it so my blog posts were listed as node/{number} in my sitemap rather than the path auto path.  After much searching it looks like the module weight on XML Sitemap was set to 2 so it was checking the nodes path before path-auto was setting the path alias.

My proof of concept pages finally got indexed by google but they only show the xml results in the description, not the rendered HTML (from the XSLT).
It turns out google may report it's self as a mozilla browser but they don't apply XSLT translations, they just present the XML in it's data form.
So the moral of the story is always render the html server side if you think the viewer is a bot (if you use code igniter use their user agent library with is_robot())