The model viewer has the ability to get properties by passing a filter: viewer.model.getBulkProperties(dbIds, ['externalId', 'Category'], function) where we can limit the results to just the two properties 'externalId' and 'Category'.
It would be a huge benefit for us to have this same filtering capability from the model derivative api: https://developer.autodesk.com/en/docs/model-derivative/v2/reference/http/urn-metadata-guid-properties-GET/
We have Revit files with 40,000+ parts, and it can take over 15 minutes to query for properties, but we are getting far more data than we need.