Optimize the source code of a single page
Microsoft Expression Web can remove specified HTML from the current web page, such as comments in your source code, unnecessary whitespace, unused styles, and empty tags.
If you want to optimize the source code of an entire site, you can set Expression Web to do so when you publish your site. That method removes specified code from those pages only when you publish them to your remote site. It maintains that code in the pages on the local site. For more information, see Optimize the source code of a site.