In what scenario might multicast traffic be slowed in a switch?

The scenario where multicast traffic might be slowed in a switch is when IGMP (Internet Group Management Protocol) snooping is enabled. IGMP snooping allows a switch to listen (snoop) to the IGMP traffic between hosts and multicast routers to manage multicast group memberships more effectively. By doing this, the switch can optimize multicast traffic flows by ensuring that multicast data is only sent out on the necessary ports, rather than flooding all ports.

Although IGMP snooping enhances the efficiency of multicast traffic management, it can introduce additional processing overhead as the switch must constantly monitor and manage the multicast group memberships. This monitoring can potentially slow down multicast traffic, especially in networks with a high volume of multicast streams or frequent membership changes. Essentially, while IGMP snooping is beneficial for reducing unnecessary traffic, it can also lead to delays if the switch has to work harder to track and manage the multicast groups.