This is a port of HTMLDOC, which can:
   Convert HTML files to PDF or PostScript
      Generate a table-of-contents for books
      Generate indexed HTML files
      Generate files on-the-fly for web applications, from the
	command-line for batch jobs, or from a GUI for interactive work.

   HTMLDOC Provides
       A command-line interface for batch and WWW applications.
       A graphical interface for interactive work.

In my opinion, HTMLDOC is *fast*, compared to the other solutions I've seen.

HTMLDOC is available under the GPL.
Commercial support is available from the author.

WWW: http://michaelrsweet.github.io/htmldoc