The Profile API does not use a cache, so repeated calls to its functions results in a database query being executed multiple times to retrieve the same data (e.g. profile_ensure_can_update() followed by profile_get_row() and profile_is_global() in account_prof_edit_page.php and account_prof_update.php).

This is generally not an issue, as in most cases the API is only called to retrieve data for a single profile (e.g. IssueAddCommand.php, mc_api.php, filter_form_api.php...)

Considering this, implementing a caching mechanism would probably be overkill, but a simple refactoring of the API to return an object for the read-only functions would allow a single SQL query to get the data, and improve the code by encapsulating logic.