How does Camunda generate a process instance?


We are evaluating Camunda to implement a long process of payments in a bank. Because of we recived a lot of payments per day (about 50,000), we need to know how Camunda generate each process instance. I mean, the bpmn (and dmn) is loaded to memory in the first execution of the process, and the next executions read the bpmn (and dmn) of memory?, or, is the bpmn (and dmn) read from XML or DB for each process execution?

Thanks in advance

the BPMN XML is stored in cache after the first call.