Convergence occurs when all ports on bridges and switches have transitioned to either the forwarding or blocking states. No data is forwarded until convergence is complete. Before data can be forwarded again, all devices must be updated.
What does a switch do when a frame is received on an interface and the destination hardware address is unknown or not in the filter table?
If you have a server or other devices connected into your switch that you're totally sure won't create a switching loop if STP is disabled, you can use something called portfast on these ports. Using it means the port won't spend the usual 50 seconds to come up while STP is converging.