After trying many different fixes for my intermittent slow WiFI problem, I found one that really helped.
I installed a free program called "Inssider" inSSIDer Wi-Fi Scanner | MetaGeek on my PC laptop and used it to detect the other WiFi systems transmitting into my location. It provides info on the strength of their signal and the channel they are using. I then changed my wireless router to an unused channel and I now get constant WiFi speed.
It's interesting that my laptop had no problem ignoring the interference from other wireless systems, but they sure messed up the iPad. The signal strength of those other signals was very weak and they didn't even register in the iPad list of available wireless networks.
For the network geeks out there, the other signals were a minimum of 30 dBm below my router's signal.