If your iPad is slow or stutters when viewing video over the internet (e.g. from YouTube), and changing your network's DNS settings, or rebooting the iPad, or changes to the Airport Extreme (or other access point) frequency/band/channel/power/multicast etc. does not fix the issue, here is a possible fix.
Check to see if your Airport Extreme Base Station has DHCP/NAT turned on. If so, instead set your AEBS to Bridge Mode (this will probably work on Airport Express too). This assumes you have a cable modem or other router/switch that you can use instead for DHCP/NAT. No more slow/stuttering video.
[crarko adds: I restart my Airport Extreme every few weeks just to flush the memory and have not experienced any trouble paying video. I do use it for DHCP/NAT on my network.
What I have noticed is that after prolonged use, my Apple TV (2nd generation) does have stuttering and will sometimes just lose it's connection to, say, Netflix. I have to reboot the Apple TV to clear that up, so I don't think it's an issue with the Airport.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20110203085732104