Only the first page of patients from the fhir patients query is actually loaded. All other patients are never loaded. The output of the fhir query is actually paginated and you have to deal with the "next" links that it contains to retrieve all patients. There is a way to increase the maximum number of patients that get included in one query, so a first step would be to increase that number. But even that maximum can only be so large and at some point one has to deal with the pagination.
Only the first page of patients from the fhir patients query is actually loaded. All other patients are never loaded. The output of the fhir query is actually paginated and you have to deal with the "next" links that it contains to retrieve all patients. There is a way to increase the maximum number of patients that get included in one query, so a first step would be to increase that number. But even that maximum can only be so large and at some point one has to deal with the pagination.