Operations which add or modify records sometimes need to perform an internal query to obtain type information for the relevant attributes. In principle it is possible for the database schema to change between update operations, and hence this query is run for each update operation. This can be a significant overhead.
For tables which are guaranteed to have a constant schema, you can optimize performance by adding a cache of these internal query results, using the function
LispWorks User Guide and Reference Manual - 21 Dec 2011