Api causing unecessary queries

The API getfields returns custom fields as well as entity fields but I noticed that when the entity is a type that doesn't have custom fields associated with it it does an unecessary DB query

I think

_civicrm_api_get_custom_fields($entity, &$params){

Should be able to call

CRM_Core_BAO_CustomGroup::mapTableName($entity)

To determine if an entity has custom fields (rather than coding a list into the API).

But in order to work need to sort out the fact that api deals in both lower case & camel case entity names & also be able to pass a param where the :default on the switch would return false at that point.

Otherwise we could create a new function but that seems like a worse practice