Came across this issue when I connected at my parents house to wifi.
I found tinkering with the Wifi settings helped considerably, but it is a bit techie. It can be a couple of things (the wifi radio in the ipad is a pretty weak one and like the iphone, it depends on where and how you hold the device).
Couple of possible:
(Easy)
Temporary fix (or to test it's an ipad issue) if possible switch the wifi router to "n" mode, see if that makes it faster.
Try disabling your "ask to join" on the ipad. Don't know why, but others have found this helps.
(Techie)
Reset and unplug everything (router, ipad etc) then start up again, but instead of automatically searching for a network input the network manually under "other".
One of the main issues is good old apple and compatibility again. If you can access your router settings, disable the QoS (Quality of Service), that should solve all download issues and you can switch the router back to mix mode.