Refers to a configuration option utilised within mt-config.cgi that enables/disables MT from performing some background tasks, eg rebuilding pages.
This option is disabled by default because it conflicts with a number of environments, particular Windows, FastCGI, mod_perl. Background tasks should only be used if FastCGI or mod_perl are not available as the latter are far more reliable and, under them, application speed much more consistent across all functionality.
To enable background tasks
Add the following line to your mt-config.cgi file
For more information refer to the Movable Type Documentation pages: D: Configuration Directives - LaunchBackgroundTasks