What is _with variables for? Why some blocks have them and some not?
_with input variable is a system enum, that tells if need to get data from relations (if there any relations between models). By default _with is not set and you will get only IDs of records from related data models. Every enabled _with increases the overall load of your application because of increasing database requests to get additional data. In genera, _with works as classic JOIN operation for Relational DBs.