I'm on PHP 5.4 and not planning to change to PHP 5.5 any time soon because I have both vB and XF sites, and vB seems to have some issues with PHP 5.5. I'm on a single, dedicated server running Litespeed webserver with Litespeed cache. I'm currently using Xcache but was thinking of uninstalling that and installing Opcache + either APCU or Memcached. Would this change make a noticeable difference to site performance? Appreciate any insights from those who have tried this.