The time taken by the agents to resolve a ticket to the satisfaction of the customer is the resolution time. Ticket resolution time that depends on the priority of the ticket in question. Companies usually set up an SLA that defines the time within which tickets need to be resolved.
When the resolution of a ticket takes a lot of time, the customer gets frustrated. Or worse, they lose faith in your system. So, admins have to make sure that agents have everything that will help them resolve tickets quickly at their fingertips; something like a set of knowledge base articles visible only to them on how to solve tricky but recurrent issues.