Daniel0524,
Do you have "Drop Broadcast and Multicast" enabled on the Virtual AP of your Wireless LAN?
Please go to Configuration> Wireless LAN> AP Configuration. Edit the AP-Group that your access points are in.
Expand Wireless LAN. Expand Virtual AP. Click on your first Virtual AP. In the Right Pane, is "Drop Broadcast and Multicast" and"Convert Broadcast ARP requests to unicast" option enabled? If not, enable both of them immediately, then click apply in the lower right hand corner. Do this for all your Virtual APs in the list.
A considerable amout of airtime is consumed by broadcasts on the network and these options shut them off. This is a routine troubleshooting step on wireless LANs and is at the heart of a great deal of congestion/performance issues, so please enable it and let us know if things are different.