All websites that use PHP or a PHP based webapplication will be a lot faster as of today. We installed the latest version of PHP5 and also enabled eaccelerator by default.

Some users reported that the strip_tags function in our PHP install was unable to return a string longer then 255 characters. We found out this was a bug in the PHP version that Debian was shipping. Finally the PHP team has patched this bug so we upgraded our PHP install to make the applications which use strip_tags happy again.

After some months of testing we also found that eaccelerator is mature and stable. After the PHP upgrade we also installed and enabled this zend_module to speedup PHP applications.
eaccelerator compiles the PHP scripts and stores this compiled copy in memory and disk. This means a PHP script is only interpretted once and all calls that follow will directly use the precompiled version. Tests show a speed increase of roughly 70% on all our CMS based websites.