HTML::Mason is a Perl-based web site development and delivery system. Its main features include:

Components written in the Mason syntax are translated to pure Perl code and cached. The optimal usage scenario of HTML::Mason is to load it in a mod_perl environment within an Apache web server. This way, compiled Perl code stays in memory and is reloaded only when the source is changed. HTML::Mason is highly customizable and is distributed freely as open source. You can get it at CPAN.

The Mason's website is at

The alternative systems, with slightly different functionality and philosophy, are HTML::EP, HTML::Embperl, eperl.