To maintain proper Wi-Fi network performance, limit the number of active SSIDs to reduce channel overhead used by network management frames, especially beacons. Enabling too many concurrent SSIDs results in more network overhead from beacons. This can cause performance degradation by utilizing a large amount of available airtime on the channel.
The Revolution Wi-Fi SSID Overhead Calculator lets you determine the amount of overhead on the wireless network based on the minimum data rate, number of SSIDs, number of neighboring APs on a channel, and size of the beacon frame.