I have written a process builder that should create/ update child records when 1000s of parents records are updated from external system. However process builder seems to throw error for these records, examples are-

ERROR: We can't save this record because the PROCESSBUILDER process failed. Give your Salesforce admin these details. This error occurred when the flow tried to create records: CANNOT_INSERT_UPDATE_ACTIVATE_ENTITY: CaseTrigger: System.LimitException: Too many DML statements: 151. You can look up ExceptionCode values in the SOAP API Developer Guide. Error ID: 723127467-93191 (-1369958504)

ERROR: We can't save this record because the PROCESSBUILDER process failed. Give your Salesforce admin these details. This error occurred when the flow tried to update records: CANNOT_EXECUTE_FLOW_TRIGGER: We can't save this record because the PROCESS BUILDER process failed. Give your Salesforce admin these details. This error occurred when the flow tried to update records: REQUEST_RUNNING_TOO_LONG: Your request was running for too long, and has been stopped.. You can look up ExceptionCode values in the SOAP API Developer Guide. Error ID: 2146764366-2599833 (1255675226). You can look up ExceptionCode values in the SOAP API Developer Guide. Error ID: 2146764366-2599835 (1022480718)

Please tell me how can I make process builder work for this scenario.

Thanks