Quick Localisation allows site admins to patch WordPress translations of any theme and any plugin without leaving the control panel
The bigger the database, the more parsing the plugin has to perform, the higher the load. The relationship is exponential. Though we tested it with thousand words and the extra load was minimal.
WordPress activates plugins alphabetically or in the order provided by the file system. Having said this, if one of these earlier plugins localises its strings directly on the initialisation, Quick Localisation won't be able to catch those.
A known way around it is as follows:
<?php include_once ABSPATH . "wp-content/plugins/quick-localization/index.php"; ?>