The following are the changes in RC3:
Fixed : Missing quote in Xanthia init script preventing successful install under certain configurations
Fixed : Removed unneeded short urls global from all theme.php's
Fixed : Added ADODB error checks to queries during engine initialisation (pnuserapi.php). See note 1.
Fixed : Added check for valid engine object after engine initialisation (all theme.php's). See note 1.
Fixed : Added missing </head> tag in piterpanv2 theme (master.htm)
Fixed : Correct smarty variable case in table1 and table2 templates - prevented old style module output from displaying.
Fixed : .7x category/theme overides now work in Xanthia themes.
Updated : Many functions how have internal in memory caches to avoid repeated db queries. This enhances performance.
Updated : Xanthia themes now include header and footer html so master.htm now represents an entire page.
Updated : Xanthia now uses new database connection method (credit to Eric Barr for this code).
Updated : Output filters now only operate on the final master template to avoid repeated replacements on sub templates.
Updated : Engine now uses assign by reference on all dynamic content - reduces memory usage.
New : Caching of block zones, palettes and theme settings in pnTemp/Xanthia_Config via Generate Config Cache admin option.
New : Full page caching available via admin panel. Modules can be excluded from full page caching via the admin panel.
New : modulestylesheets plugin allows loading of per module stylesheets (stored in modules/<modname>/pnstyle).
New : New plugin to generate standard PN header and footer (additional_header, pagerendertime, lang, keywords, charset).
New : visual editor plugins for typetool v55 (PN .72x), typetool v8 (larsneo's new version) and htmlarea (.8x).
Download it here