We have a 5508 controller running 8.0100 software. We have a mixture of 1141, 1600, 3600 and 3700 AP's. In one particular building where most of the space it open plan, we are getting strange problems with WiFi, particularly with slow download times. In other areas the speeds are perfect. The building has a high density installation of 1600 AP's. In some areas of the building speeds are fine, in others the speeds are awful.
Having just got back to my desk after running a site survey using inSSIDER I find that we have a lot of co-channel interference.
Very hard to say. To start with , check Throughput between wireless/Wired and then between wireless/wireless and wired/wired using Iperf to conclude if it is a really a wireless issue.
If it is high density installation , check the power levels of few Aps if they are at low power levels.
Is it on both 802.11a/802.11bb band. During downtime disable the specific radios of your APs 802.11a or 802.11b/g for the APs located at strategic points (in the middle causing Interference" and then check.