WiFi Clients: slow speeds

I'm troubleshooting a deployment of a wireless solution on a AP100 (9.0.001) hosted out of a XG125 (16.05.8).

We are having a horrendous hit on the data rates when running through the wireless.  While we see an average of 20/11 across the wired connection the wireless is dropping back to 3/8.  We threw an Apple Airport Express in for testing and on that wireless we see an 8/8.  The client is (understandably) upset with these results.  We are not encountering a huge volume of users, average of 8-10 devices.  We have two SSIDs pushing out, however all the users are only on one of them.  The security mode is WPA2 Personal, and using AES only.

I have disabled ALL Scanning, Intrusion Prevention, Traffic Shaping, Web Policy, Application Control from the firewall rules.  I am unsure how to proceed from a tuning stand-point.

Apologies if this topic has already been broached, I couldn't find anything that sounded similar to what we are experiencing.