Database fulltext indices
In version 5.6 MySQL introduced a feature called fulltext indices. LiveAgent application utilizes the fulltext indexes to speed up searching in contacts (if you don't use Elasticsearch), but it is also used in filtering tickets by tags and filtering contacts by contact groups.
If you install LiveAgent on database MySQL 5.6 or higher, the columns are already created with fulltext indices and you don't need to do anything. However, if you installed LiveAgent on database version MySQL 5.5 or older...