The phrase "heavy caseload" refers to having a large amount of work or responsibilities to handle. It often implies a significant amount of work that can be challenging and time-consuming. Full definition
Right now, more than half of Americans live in jurisdictions facing what the Administrative Office of the U.S. Courts calls «judicial emergencies»: their empty benches can't handle heavy caseloads. (sentencing.typepad.com)
... To require trial judges charged with heavy caseloads of criminal cases to deal in their reasons with every aspect of every case would slow the system of justice immeasurably. (slaw.ca)
I wasn't even looking for a mid morning snack after the very heavy caseload. (ohsheglows.com)