Get permissions for all resources of a specific role/user

For a current project it is required to display the effective permissions for the complete repository for a specific role/user. Currently we are achieving that by querying the repository recursive via REST-API (rest_v2/resources/) and then execute a single request for each resource to the permissions service (rest_v2/permissions/). For larger repositories, this generates a lot of requests and works poorly from a performance standpoint.

Is there a better way to get the effective permissions for the all resources of a role/user, preferably via REST-API?